Theory CSP_Laws

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―‹ ********************************************************************
 * Project         : HOL-CSP - A Shallow Embedding of CSP in  Isabelle/HOL
 * Version         : 2.0
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 * Author          : Burkhart Wolff, Safouan Taha, Lina Ye, Benoît Ballenghien.
 *                   (Based on HOL-CSP 1.0 by Haykal Tej and Burkhart Wolff)
 *
 * This file       : A Combined CSP Theory
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chapter‹ The "Laws" of CSP ›

theory CSP_Laws                                               
  imports Bot Skip Stop Det Ndet Mprefix Mndetprefix Seq Hiding Sync Renaming
          "HOL-Eisbach.Eisbach"
begin 

method exI for y::'a = (rule_tac exI[where x = y])


section‹ General Laws›

lemma SKIP_Neq_STOP: "SKIP  STOP"
  by (auto simp: Process_eq_spec F_SKIP F_STOP D_SKIP D_STOP Un_def)

lemma BOT_less1[simp]: "  (X::'a process)"
  by (simp add: le_approx_implies_le_ref)

lemma BOT_less2[simp]: "BOT  (X::'a process)"
  by simp

section‹ Deterministic Choice Operator Laws ›

lemma mono_Det_FD_onside[simp]: " P  P'  (P  S)  (P'  S)"
  unfolding le_ref_def F_Det D_Det using F_subset_imp_T_subset by blast

lemma mono_Det_FD[simp]: " P  P'; S  S'  (P  S)  (P'  S')"
  by (metis Det_commute dual_order.trans mono_Det_FD_onside)

lemma mono_Det_ref: " P  P'; S  S'  (P  S)  (P'  S')"
  using below_trans mono_Det mono_Det_sym by blast

lemma Det_BOT : "(P  ) = "
  by (auto simp add:Process_eq_spec D_Det F_Det is_processT2 D_imp_front_tickFree F_UU D_UU) 

lemma Det_STOP: "(P  STOP) = P"
  by (auto simp add: Process_eq_spec D_Det F_Det D_STOP F_STOP T_STOP 
                      Un_def Sigma_def is_processT8 is_processT6_S2)  

lemma Det_id: "(P  P) = P"
  by (auto simp: Process_eq_spec D_Det F_Det Un_def Sigma_def is_processT8 is_processT6_S2)

lemma Det_assoc: "((M  P)  Q) = (M  (P  Q))"
  by (auto simp add: Process_eq_spec D_Det F_Det Un_def Sigma_def T_Det)  


section‹ NonDeterministic Choice Operator Laws ›

lemma mono_Ndet_FD[simp]: " P  P'; S  S'  (P  S)  (P'  S')"
  by (auto simp: le_ref_def F_Ndet D_Ndet)

lemma mono_Ndet_FD_left[simp]: "P  Q  (P  S)  Q" 
  by (metis D_Ndet F_Ndet dual_order.trans le_ref_def le_sup_iff order_refl)

lemma mono_Ndet_FD_right[simp]: "P  Q  (S  P)  Q" 
  by (metis D_Ndet F_Ndet dual_order.trans le_ref_def le_sup_iff order_refl)

lemma mono_Ndet_ref: " P  P'; S  S'  (P  S)  (P'  S')"
  using below_trans mono_Ndet mono_Ndet_sym by blast

lemma Ndet_BOT: "(P  ) = "
  by (auto simp: Process_eq_spec D_Ndet F_Ndet is_processT2 D_imp_front_tickFree F_UU D_UU)

lemma Ndet_id: "(P  P) = P"
  by (simp_all add: F_Ndet D_Ndet Process_eq_spec)  

lemma Ndet_assoc: "((M  P)  Q) = (M  (P  Q))"
  by (simp_all add: F_Ndet D_Ndet  Process_eq_spec Un_assoc)  

subsection‹ Multi-Operators laws  ›

lemma Det_distrib: "(M  (P  Q)) = ((M  P)  (M  Q))"
  by (auto simp add:  Process_eq_spec F_Det D_Det F_Ndet D_Ndet Un_def T_Ndet)

lemma Ndet_distrib: "(M  (P  Q)) = ((M  P)  (M  Q))"
  by (auto simp add:  Process_eq_spec F_Det D_Det F_Ndet 
                      D_Ndet Un_def T_Ndet is_processT8 is_processT6_S2)

lemma Ndet_FD_Det: "(P  Q)  (P  Q)"
  apply(auto simp add:le_ref_def D_Ndet D_Det F_Ndet F_Det T_Ndet T_Det Ra_def min_elems_def) 
  using is_processT6_S2 NF_ND by blast+


section‹ Sequence Operator Laws ›

subsection‹Preliminaries›

definition F_minus_D_Seq where 
    "F_minus_D_Seq P Q  {(t, X). (t, X  {tick})   P  tickFree t} 
                                {(t, X). t1 t2. t = t1 @ t2  t1 @ [tick]  𝒯 P  (t2, X)   Q}"

lemma F_minus_D_Seq_opt: "(a,b)  (P ; Q) = (a  𝒟(P ; Q)  (a,b)  F_minus_D_Seq P Q)"
  using NF_ND by (auto simp add: F_Seq D_Seq F_minus_D_Seq_def) blast+
  

lemma Process_eq_spec_optimized_Seq : 
"((P ; Q) = (U ; S)) = (𝒟 (P ; Q) = 𝒟 (U ; S)  
                            F_minus_D_Seq P Q   (U ; S)  
                            F_minus_D_Seq U S   (P ; Q))"
  unfolding Process_eq_spec_optimized[of "(P ; Q)" "(U ; S)"] 
  by (auto simp:F_minus_D_Seq_opt)

subsection‹Laws›

lemma mono_Seq_FD[simp]: " P  P'; S  S'  (P ; S)  (P' ; S')"
  apply (auto simp: le_ref_def F_Seq D_Seq)
  by (metis F_subset_imp_T_subset subsetCE)+

lemma mono_Seq_ref: " P  P'; S  S'  (P ; S)  (P' ; S')"
  using below_trans mono_Seq mono_Seq_sym by blast

lemma BOT_Seq: "( ; P) = "
  by (simp add: BOT_iff_D D_Seq D_UU)
   

lemma Seq_SKIP: "(P ; SKIP) = P"
  apply (auto simp add: Process_eq_spec F_Seq F_SKIP D_Seq D_SKIP T_F_spec is_processT6_S1)
      apply (use is_processT4 in blast)
     apply (meson append_single_T_imp_tickFree is_processT5_S7 non_tickFree_tick tickFree_append)
    apply (meson is_processT8)
   apply (use T_F_spec insert_absorb is_processT5_S2 in fastforce)
  by (metis F_T is_processT nonTickFree_n_frontTickFree)

lemma SKIP_Seq: "(SKIP ; P) = P"
  by (auto simp add: Process_eq_spec D_Seq T_SKIP F_Seq F_SKIP D_SKIP is_processT8_Pair)

lemma STOP_Seq: "(STOP ; P) = STOP"
  by (simp add: STOP_iff_T T_Seq T_STOP F_STOP D_STOP Collect_conv_if)


subsection‹ Multi-Operators laws  ›

lemma Seq_Ndet_distrR: "((P  Q) ; S) = ((P ; S)  (Q ; S))"
  by (auto simp add: Process_eq_spec D_Seq D_Ndet T_Ndet Un_def F_Seq T_Seq F_Ndet)

lemma Seq_Ndet_distrL: "(P ; (Q  S)) = ((P ; Q)  (P ; S))"
  by (auto simp add: Process_eq_spec D_Seq D_Ndet T_Ndet Un_def F_Seq F_Ndet)

lemma Seq_assoc_D: "𝒟 (P ; (Q ; S)) = 𝒟 ((P ; Q) ; S)"
proof(safe, goal_cases)
  show s  𝒟 (P ; (Q ; S))  s  𝒟 (P ; Q ; S) for s
    by (simp add: D_Seq T_Seq) (metis append.assoc)
next
  fix s
  assume s  𝒟 (P ; Q ; S)
  thus s  𝒟 (P ; (Q ; S))
  proof(auto simp add:D_Seq T_Seq, goal_cases)
    case (1 t1 t2 t1a t2a)
    from "1"(1)[rule_format, OF "1"(5)] show ?case
      apply (cases tickFree t2a)
       apply (metis "1"(4) "1"(5) append_single_T_imp_tickFree non_tickFree_tick tickFree_append)
      by (metis "1"(3) "1"(4) "1"(6) T_nonTickFree_imp_decomp append.assoc butlast_snoc)
  next
    case (2 t1 t2)
    then show ?case 
      by (meson D_imp_front_tickFree front_tickFree_implies_tickFree is_processT7 is_processT9_S_swap)
  qed
qed
  
lemma Seq_assoc: "(P ; (Q ; S)) = ((P ; Q) ; S)"
proof (auto simp: Process_eq_spec_optimized_Seq Seq_assoc_D, goal_cases)
  case (1 a b)
  then show ?case
  proof(auto simp add:F_minus_D_Seq_def Seq_assoc_D F_minus_D_Seq_opt append_single_T_imp_tickFree 
             del:conjI, 
        goal_cases 11 12)
    case (11 t1 t2)
    then show ?case by (metis (mono_tags, lifting) D_Seq Seq_assoc_D UnCI mem_Collect_eq)
  next
    case (12 t1 t1a t2a)
    hence "(t1 @ t1a) @ [tick]  𝒯 (P ; Q)" by (auto simp:T_Seq)
    then show ?case
      using 12(2)[rule_format, of "t1@t1a" t2a] 12(4,5,6) by simp
  qed
next
  case (2 a b)
  then show ?case
  proof(auto simp add:F_minus_D_Seq_def Seq_assoc_D F_minus_D_Seq_opt 
                       append_single_T_imp_tickFree T_Seq del:conjI, 
      goal_cases 21 22 23)
    case 21
    then show ?case
      using D_Seq by force
  next
    case (22 t1 t2 t1a t2a)
    then obtain t2b where  "t2a = t2b@[tick]"
      by (metis T_nonTickFree_imp_decomp append_single_T_imp_tickFree non_tickFree_tick tickFree_append)
    with 22 show ?case using append.assoc butlast_snoc by auto
  next
    case (23 t1 t2)
    hence "t1  𝒟 (P ; (Q ; S))" 
      by (simp add: D_Seq) (meson is_processT9_S_swap)
    with 23 Seq_assoc_D show ?case by (metis front_tickFree_implies_tickFree process_charn)
  qed
qed


section‹ The Multi-Prefix Operator Laws ›

lemma mono_Mprefix_FD[simp]: "x  A. P x  P' x  Mprefix A P  Mprefix A P'"
  by (auto simp: le_ref_def F_Mprefix D_Mprefix) blast+

lemmas mono_Mprefix_ref =  mono_Mprefix0

lemma Mprefix_STOP: "(Mprefix {} P) = STOP"
  by (auto simp:Process_eq_spec F_Mprefix D_Mprefix D_STOP F_STOP)

subsection‹ Multi-Operators laws  ›

lemma Mprefix_Un_distrib: "(Mprefix (A  B) P) = ((Mprefix A P)  (Mprefix B P))"
  apply (unfold Process_eq_spec, rule conjI)
  apply (auto, (elim disjE conjE | simp_all add: F_Det F_Mprefix Un_def image_def)+, auto)
  by (auto simp add: D_Det D_Mprefix Un_def)

lemma Mprefix_Seq: "((Mprefix A P) ; Q) = (Mprefix A (λx. (P x) ; Q))"
proof (unfold Process_eq_spec, rule conjI, rule subset_antisym, goal_cases)
  case 1
  then show ?case   
    apply(unfold split_def F_Seq D_Seq F_Mprefix T_Mprefix D_Mprefix)
    apply(rule subsetI, simp_all, elim disjE conjE exE)
        apply(rule disjI1, simp, meson tickFree_tl)
       apply (rule disjI2, rule conjI, simp) apply auto[1]
      apply (auto simp add:hd_append)[1]
   using tickFree_tl by fastforce
next
  case 2
  then show ?case 
    apply(unfold split_def F_Seq D_Seq F_Mprefix T_Mprefix D_Mprefix)
    apply(rule subsetI, simp_all, elim disjE conjE exE)
        apply(rule disjI1, simp, blast)
       apply(rule disjI1, metis event.simps(3) list.exhaust_sel tickFree_Cons)
  proof(goal_cases)
    case (1 x a t1 t2)
    then show ?case 
      apply(rule_tac disjI2, rule_tac disjI1, rule_tac x="(ev a)#t1" in exI) 
      using hd_Cons_tl image_iff by fastforce
  next
    case (2 x a)
    then show ?case     
      by (metis prod.collapse)
  qed
next
  case 3
  then show ?case     
    apply (auto simp add: D_Mprefix D_Seq T_Mprefix)
      apply (metis event.distinct(1) hd_append image_iff list.sel(1))
     apply (metis event.distinct(1) hd_append list.sel(1) tl_append2)
    by (metis Cons_eq_appendI hd_Cons_tl list.sel(1) list.sel(3))
qed

subsection‹ Derivative Operators laws  ›

lemma Mprefix_singl: "(Mprefix {a} P) = (a  (P a))"
  by (simp add:write0_def Mprefix_def, rule arg_cong[of _ _ "λx. Abs_process x"]) fastforce

lemma mono_read_FD: "(x. P x  Q x)   (c?x  (P x))  (c?x  (Q x))"
  by (simp add: read_def)

lemma mono_write_FD: "(P  Q)   (c!x  P)  (c!x  Q)"
  by (simp add: write_def)

lemma mono_write0_FD: "P  Q  (a  P)  (a  Q)"
  by (simp add: write0_def)

lemma mono_read_ref: "(x. P x  Q x)   (c?x  (P x))  (c?x  (Q x))"
  by (simp add: mono_Mprefix0 read_def)
                                         
lemma mono_write_ref: "(P  Q)   (c!x  P)  (c!x  Q)"
  by (simp add: mono_Mprefix0 write_def)

lemma mono_write0_ref: "P  Q  (a  P)  (a  Q)"
  by (simp add: mono_Mprefix0 write0_def)

lemma write0_Ndet: "(a  (P  Q)) = ((a  P)  (a  Q))"
  by (auto simp: Process_eq_spec write0_def D_Ndet F_Ndet F_Mprefix D_Mprefix Un_def)

lemma write0_Det_Ndet: "((a  P)  (a  Q)) = ((a  P)  (a  Q))"
  by (auto simp: Process_eq_spec write0_def D_Ndet F_Ndet F_Det D_Det) (simp add: F_Mprefix)+

lemma Mprefix_Det: (eA  P e)  (eA  Q e) = eA  (P e  Q e)
  by (auto simp: Process_eq_spec F_Det D_Det) (auto simp: D_Ndet F_Ndet F_Mprefix D_Mprefix)

section‹ The Hiding Operator Laws ›

subsection‹ Preliminaries ›

lemma elemDIselemHD: t  𝒟 P  trace_hide t (ev ` A)  𝒟 (P \ A)
proof (cases "tickFree t")
  case True
  assume "t  𝒟 P"
  with True show ?thesis by (simp add:D_Hiding, rule_tac x=t in exI, rule_tac x="[]" in exI, simp)
next
  case False
  assume a:"t  𝒟 P"
  with False obtain t' where "t = t'@[tick]" using D_imp_front_tickFree nonTickFree_n_frontTickFree by blast
  with a show ?thesis apply (auto simp add:D_Hiding, rule_tac x=t' in exI, rule_tac x="[tick]" in exI)  
    by (meson front_tickFree_implies_tickFree front_tickFree_single is_processT)
qed

lemma length_strict_mono: "strict_mono (f::nat  'a list)  length (f i)  i + length (f 0)"
  apply(induct i, simp)
  by (metis dual_order.trans lessI less_length_mono not_less not_less_eq_eq plus_nat.simps(2) strict_mono_def)

lemma mono_trace_hide: "a  b  trace_hide a (ev ` A)  trace_hide b (ev ` A)"
  by (metis filter_append le_list_def)

lemma mono_constant: 
  assumes "mono (f::nat  'a event list)" and "i. f i  a"
  shows "i. ji. f j = f i"
proof -
  from assms(2) have "i. length (f i)  length a"
    by (simp add: le_length_mono)
  hence aa:"finite {length (f i)|i. True}" 
    using finite_nat_set_iff_bounded_le by auto
  define lm where l2:"lm = Max {length (f i)|i. True}"
  with aa obtain im where "length (f im) = lm" using Max_in by fastforce
  with l2 assms(1) show ?thesis 
    apply(rule_tac x=im in exI, intro impI allI)
    by (metis (mono_tags, lifting) Max_ge aa antisym le_length_mono le_neq_trans less_length_mono 
              mem_Collect_eq mono_def order_less_irrefl)
qed
  
lemma elemTIselemHT: t  𝒯 P  trace_hide t (ev ` A)  𝒯 (P \ A)
proof (cases "tickFree t")
  case True
  assume a:"t  𝒯 P"
  with True show ?thesis
  proof (cases "(ta. trace_hide t (ev ` A) = trace_hide ta (ev ` A)  (ta, ev ` A)   P)")
    case True
    thus ?thesis by (simp add:T_Hiding)
  next
    case False
    with a False inf_hidden[of A t P] obtain f where "isInfHiddenRun f P A  t  range f" by auto
    with True show ?thesis 
      by (simp add:T_Hiding, rule_tac disjI2, rule_tac x=t in exI, rule_tac x="[]" in exI, auto)
  qed
next
  case False
  assume a:"t  𝒯 P"
  with False obtain t' where tt:"t = t'@[tick]" using T_nonTickFree_imp_decomp by auto
  with a show ?thesis 
  proof (cases "(ta. trace_hide t (ev ` A) = trace_hide ta (ev ` A)  (ta, ev ` A)   P)")
    case True
    thus ?thesis by (simp add:T_Hiding)
  next
    case False
    assume "t  𝒯 P"
    with False inf_hidden[of A t P] obtain f where "isInfHiddenRun f P A  t  range f" by auto
    then show ?thesis 
      apply (simp add:T_Hiding, rule_tac disjI2, rule_tac x=t' in exI, rule_tac x="[tick]" in exI, auto)
        apply (metis append_T_imp_tickFree list.distinct(1) tt)
       using tt apply force
      by (metis False append_T_imp_tickFree is_processT5_S7 non_tickFree_tick not_Cons_self2 tickFree_append tt)
  qed
qed

lemma Hiding_Un_D1: 𝒟 (P \ (A  B))  𝒟 ((P \ A) \ B)
proof (simp add:conj_commute D_Hiding, intro conjI subset_antisym subsetI, simp_all, goal_cases)
  case (1 x)
  then obtain t u where B1:"x = trace_hide t (ev ` (A  B)) @ u" 
                    and B2:"tickFree t" and B3:"front_tickFree u" 
                    and B4:"(t  𝒟 P  ((f:: nat  'a event list). isInfHiddenRun f P (A  B) 
                                                                       t  range f))" by auto
  thus ?case
    apply(erule_tac  disjE)
    apply(rule_tac x="trace_hide t (ev ` A)" in exI, rule_tac x=u in exI)
    apply(simp add:Hiding_tickFree tickFree_def)
    apply(rule disjI1, rule_tac x=t in exI, rule_tac x="[]" in exI, simp) 
  proof(goal_cases)
    case 1
    then obtain f n where fc:"isInfHiddenRun f P (A  B)  t = f n" by auto
    define ff where "ff = (λi. take (i + length (f 0)) (f i))"
    with fc have ffc:"isInfHiddenRun ff P (A  B)  t  range ff" 
    proof (auto, goal_cases)
      case 1
      { fix x
        from length_strict_mono[of f "Suc x ", OF 1(2)]
        have a:"take (x + length (f 0)) (f (Suc x)) < take ((Suc x) + length (f 0)) (f (Suc x))"
          by (simp add: take_Suc_conv_app_nth)
        from 1(2)[THEN strict_monoD, of x "Suc x", simplified] 
          obtain t where "f (Suc x) = (f x @ t)" by (metis le_list_def less_imp_le)
        with length_strict_mono[of f x, OF 1(2)]
          have "take (x + length (f 0)) (f x) = take (x + length (f 0)) (f (Suc x))" by simp
        with a have "take (x + length (f 0)) (f x) < take (Suc x + length (f 0)) (f (Suc x))" by simp
      }
      thus ?case by (meson lift_Suc_mono_less strict_mono_def)
    next
      case (2 i)
      have "take (i + length (f 0)) (f i)  f i"
        using append_take_drop_id le_list_def by blast
      also have "x y. x  y  y  𝒯 P  x  𝒯 P" using is_processT3_ST_pref by blast
      ultimately show ?case using "2"(3) by blast 
    next
      case (3 i)
      hence "(f i)  (f 0)" using strict_mono_less_eq by blast
      hence "take (i + length (f 0)) (f i)  (f 0)"
        by (metis add.commute append_eq_conv_conj le_list_def take_add)
      hence a:"   [xtake (i + length (f 0)) (f i) . x  ev ` A  x  ev ` B] 
                 [xf 0 . x  ev ` A  x  ev ` B]"
        by (metis (no_types, lifting) filter_append le_list_def)
      have "take (i + length (f 0)) (f i)  f i"
        using append_take_drop_id le_list_def by blast
      hence "  [xtake (i + length (f 0)) (f i) . x  ev ` A  x  ev ` B] 
              [xf i . x  ev ` A  x  ev ` B]"
        by (metis (no_types, lifting) filter_append le_list_def)
      with a 3(4) show ?case by (metis (no_types, lifting) dual_order.antisym)
    next
      case 4
      have "f (length (f n) - length (f 0))  f n"
        by (simp add: "4"(2) add_le_imp_le_diff length_strict_mono strict_mono_less_eq)
      hence "f n = (λi. take (i + length (f 0)) (f i)) (length (f n) - length (f 0))" 
        by (metis "4"(2) add.commute append_eq_conv_conj diff_is_0_eq' 
                  le_add_diff_inverse le_list_def le_zero_eq nat_le_linear strict_mono_less_eq)
      then show ?case by blast
    qed
    thus ?case proof(cases "m. (i>m. last (ff i)  (ev ` A))")
      case True
      then obtain m where mc:"i>m. last (ff i)  (ev ` A)" by blast
      hence mc2:"tickFree (ff m)" 
        by (metis (no_types, lifting) B2 event.distinct(1) ffc 
                                      image_iff mem_Collect_eq set_filter tickFree_def)
      with mc mc2 1 ffc show ?thesis 
        apply(rule_tac x="trace_hide (ff m) (ev ` A)" in exI, rule_tac x=u in exI, simp, intro conjI)    
        apply (metis (no_types, lifting) mem_Collect_eq set_filter tickFree_def)
        apply (metis (no_types, lifting) rangeE)
        apply(rule disjI1, rule_tac x="ff m" in exI, rule_tac x="[]" in exI, intro conjI, simp_all)
        apply(rule disjI2, rule_tac x="λi. ff(i + m)" in exI, intro conjI)
           apply (metis (no_types, lifting) add.commute add.right_neutral rangeI) 
          apply (simp add: strict_mono_def)
         apply blast
        proof(rule allI, goal_cases)
          case (1 i)
          from ffc ff_def True have "t. (ff (i + m)) = (ff m) @ t  set t  (ev ` A)" 
          proof(induct i)
            case 0
            then show ?case by fastforce
          next
            case (Suc i)
            then obtain tt where tc:"(ff (i + m)) = (ff m) @ tt  set tt  (ev ` A)" by blast
            from ffc ff_def length_strict_mono[of ff] have lc:"length (ff (Suc i + m)) 
                                                              = Suc (length (ff (i + m)))" 
              by (metis (no_types, lifting) add_Suc fc length_strict_mono length_take min.absorb2)
            from True obtain l where lc2:"l = last (ff (Suc i + m))  l  (ev ` A)"
              by (meson less_add_same_cancel2 mc zero_less_Suc)
            from ffc obtain r where rc:"ff (Suc i + m) = ff (i + m)@r"
              by (metis add.commute add_Suc_right le_list_def lessI less_imp_le strict_mono_less_eq)
            with lc have "length r = 1" by (metis Suc_eq_plus1 add_left_cancel length_append)
            with rc lc2 have "r = [l]"
              by (metis (no_types, lifting) Nil_is_append_conv Suc_eq_plus1 append_butlast_last_id 
                        append_eq_append_conv append_eq_append_conv2 length_Cons length_append)
            with Suc lc2 tc rc show ?case by (rule_tac x="tt@[l]" in exI, auto) 
          qed
          then show ?case using filter_empty_conv by fastforce
        qed
    next
      case False
      { fix i
        assume as:"(i::nat) > 0"
        with ffc obtain tt where ttc:"ff i = ff 0 @ tt  set tt  ev ` (A  B)" 
          unfolding isInfHiddenRun_1 by blast
        with ffc as have "tt  []" using strict_mono_eq by fastforce
        with ttc have "last (ff i)  ev ` (A  B)" by auto
      }
      hence as2:"i. j>i. last(ff j)  ((ev ` B) - (ev ` A))"
        by (metis DiffI False UnE gr_implies_not_zero gr_zeroI image_Un)
      define ffb where "ffb = rec_nat t (λi t. (let j = SOME j. ff j > t  
                              last(ff j)  ((ev ` B) - (ev ` A)) in ff j))"
      with as2 have ffbff:"n. ffb n  range ff"
        by (metis (no_types, lifting) ffc old.nat.exhaust old.nat.simps(6) old.nat.simps(7) rangeI)
      from 1 ffb_def show ?thesis
        apply(rule_tac x="trace_hide t (ev ` A)" in exI, rule_tac x=u in exI, simp, intro conjI)
         apply (meson filter_is_subset set_rev_mp tickFree_def)        
      proof(rule disjI2, rule_tac x="λi. trace_hide (ffb i) (ev ` A)" in exI, intro conjI, goal_cases)
        case 1
        then show ?case by (metis (no_types, lifting) old.nat.simps(6) rangeI) 
      next
        case 2
        { fix n
          have a0:"(ffb (Suc n)) = ff (SOME j. ff j > ffb n  last(ff j)  ((ev ` B) - (ev ` A)))" 
            by (simp add: ffb_def)
          from ffbff obtain i where a1:"ffb n = ff i" by blast
          with as2 have "j. ff j > ffb n  last(ff j)  ((ev ` B) - (ev ` A))"
            by (metis ffc strict_mono_def)
          with a0 a1 have a:"(ffb (Suc n)) > (ffb n)  last (ffb (Suc n))  (ev ` A)"
            by (metis (no_types, lifting) Diff_iff tfl_some) 
          then obtain r where  "ffb (Suc n) =  (ffb n)@r  last r  (ev ` A)"
            by (metis append_self_conv last_append le_list_def less_list_def) 
          hence "trace_hide (ffb (Suc n)) (ev ` A) > trace_hide (ffb n) (ev ` A)"
            by (metis (no_types, lifting) a append_self_conv filter_append filter_empty_conv 
                                          last_in_set le_list_def less_list_def)
        }
        then show ?case by (metis (mono_tags, lifting) lift_Suc_mono_less_iff strict_monoI)
      next
        case 3
        then show ?case by (metis (mono_tags) elemTIselemHT ffbff ffc rangeE)  
      next
        case 4
        from ffbff ffc show ?case by (metis rangeE trace_hide_union)
      qed
    qed
  qed
qed

lemma Hiding_Un_D2: finite A  𝒟 ((P \ A) \ B)  𝒟 (P \ (A  B))
proof (simp add:conj_commute D_Hiding, intro conjI subset_antisym subsetI, simp_all, goal_cases)
  case (1 x)
  then obtain t u where B1:"x = trace_hide t (ev ` B) @ u" 
                   and  B2:"tickFree t" 
                   and  B3:"front_tickFree u" 
                   and  B4:(t  𝒟 (P \ A)  
                            ((f:: nat  'a event list). isInfHiddenRun f (P \ A) B  t  range f))
    by (simp add:D_Hiding) blast
  thus ?case
  proof(erule_tac disjE, auto simp add:D_Hiding, goal_cases)
    case (1 ta ua)
    then show ?case 
      by (rule_tac x=ta in exI, rule_tac x = "trace_hide ua (ev ` B) @ u" in exI, 
          auto simp add: front_tickFree_append tickFree_def)
  next
    case (2 ua f xa)
    then show ?case 
      apply(rule_tac x="f xa" in exI, rule_tac x="trace_hide ua (ev ` B) @ u" in exI, 
            intro conjI disjI2)
         apply(auto simp add: front_tickFree_append tickFree_def)
      by (rule_tac x="f" in exI) (metis (no_types) filter_filter rangeI)
  next
    case (3 f xx)
    note "3a" = 3
    then show ?case
    proof(cases i. f i  𝒟 (P \ A))
      case True
      with 3 show ?thesis 
      proof(auto simp add:D_Hiding, goal_cases)
        case (1 i ta ua)
        then show ?case 
        apply (rule_tac x=ta in exI, rule_tac x="trace_hide ua (ev ` B) @ u" in exI, intro conjI)
           apply (metis (full_types) front_tickFree_append Hiding_tickFree tickFree_append)
          apply(subgoal_tac "trace_hide (f xx) (ev ` B) = trace_hide (f i) (ev ` B)", auto)
         apply (metis (full_types) filter_append filter_filter)
        by (metis (full_types) filter_append filter_filter)
      next
        case (2 i ua fa xa)
        hence "trace_hide (f xx) (ev ` B) = trace_hide (f i) (ev ` B)" by metis
        with 2 show ?case
          apply (rule_tac x="fa xa" in exI, rule_tac x="trace_hide ua (ev ` B) @ u" in exI, intro conjI)
             apply (metis (full_types) front_tickFree_append Hiding_tickFree tickFree_append)
            apply (simp_all) 
          apply(rule_tac disjI2, rule_tac x=fa in exI, auto)
          by (metis (no_types) filter_filter)      
      qed
    next
      case False
      with 3 have Falsebis:i. (f i  𝒯 (P \ A)  f i  𝒟 (P \ A)) by blast
      with T_Hiding[of P A] D_Hiding[of P A] 
      have "i. (f i  {trace_hide t (ev ` A) |t. (t, ev ` A)   P})" 
        by (metis (no_types, lifting) UnE)
      hence ff0:"i. (t. f i = trace_hide t (ev ` A)  t  𝒯 P)" using F_T by fastforce
      define ff where ff1:"ff = (λi. SOME t. f i = trace_hide t (ev ` A)  t  𝒯 P)"
      hence "inj ff" unfolding inj_def by (metis (mono_tags, lifting) "3"(4) ff0 strict_mono_eq tfl_some)
      hence ff2:"infinite (range ff)" using finite_imageD by blast
      { fix tt i
        assume "tt  range ff"
        then obtain k where "ff k = tt" using finite_nat_set_iff_bounded_le by blast
        hence kk0:"f k = trace_hide tt (ev ` A)  tt  𝒯 P" using ff1 
          by (metis (mono_tags, lifting) ff0 someI_ex)
        hence "set (take i tt)  set (f i)  (ev ` A)"
        proof(cases "k  i")
          case True
          hence "set (f k)  set (f i)" 
            by (metis "3"(4) le_list_def set_append strict_mono_less_eq sup.cobounded1)
          moreover from kk0 have "set (take i tt)  set (f k)  (ev ` A)" using in_set_takeD by fastforce
          ultimately show ?thesis by blast
        next
          case False
          have a:"length (f i)  i" by (meson "3"(4) dual_order.trans le_add1 length_strict_mono)
          have b:"f i  f k" using "3"(4) False nat_le_linear strict_mono_less_eq by blast
          with a have c:"take i (f k)  (f i)"
            by (metis append_eq_conv_conj le_add_diff_inverse le_list_def take_add)
          from kk0[THEN conjunct1] have c1:"f k = (trace_hide (take i tt) (ev ` A)) @
                                                  (trace_hide (drop i tt) (ev ` A))"
            by (metis append_take_drop_id filter_append)
          have "length (trace_hide (take i tt) (ev ` A))  i"
            by (metis length_filter_le length_take min.absorb2 nat_le_linear order.trans take_all)
          with c1 have "take i (f k)  (trace_hide (take i tt) (ev ` A))" by (simp add: le_list_def)
          with c obtain t where d:"f i = (trace_hide (take i tt) (ev ` A))@t"
            by (metis append.assoc le_list_def)
          then show ?thesis using in_set_takeD by fastforce
        qed
      } note ee=this
      { fix i
        have "finite {(take i t)|t. t  range ff}" 
        proof(induct i, simp)
          case (Suc i)
          have ff:"{take (Suc i) t|t. t  range ff}  {(take i t)|t. t  range ff} 
                      (e(set (f (Suc i))  (ev ` A)). {(take i t)@[e]|t. t  range ff})" (is "?AA  ?BB")
            proof
              fix t
              assume "t  ?AA"
              then obtain t' where hh:"t'  range ff  t = take (Suc i) t'" 
                using finite_nat_set_iff_bounded_le by blast
              with ee[of t'] show "t  ?BB"
                proof(cases "length t' > i")
                  case True
                  hence ii:"take (Suc i) t' = take i t' @ [t'!i]" by (simp add: take_Suc_conv_app_nth)
                  with ee[of t' "Suc i"] have "t'!i  set (f (Suc i))  (ev ` A)" by (simp add: hh)
                  with ii hh show ?thesis by blast
                next
                  case False
                  hence "take (Suc i) t' = take i t'" by fastforce
                  with hh show ?thesis by auto
                qed
            qed
          { fix e 
            have "{x @ [e] |x. t. x = take i t  t  range ff} = {take i t' @ [e] |t'. t'  range ff}"
              by auto
            hence "finite({(take i t') @ [e] |t'. t'range ff})"
              using finite_image_set[of _ "λt. t@[e]", OF Suc] by auto 
          } note gg=this
          have "finite(set (f (Suc i))  (ev ` A))" using 1(1) by simp
          with ff gg Suc show ?case by (metis (no_types, lifting) finite_UN finite_Un finite_subset)
        qed
      } note ff=this
      hence "i. {take i t |t. t  range ff} = {t. t'. t = take i (ff t')}" by auto
      with KoenigLemma[of "range ff"] ff ff2
      obtain f' where gg:"strict_mono (f':: nat  'a event list)  
                                            range f'  {t. t'range ff. t  t'}" by auto
      { fix i
        from gg obtain n where aa:"f' i  ff n" by blast
        have "t. f n = f 0 @ t" by (metis "3a"(4) le0 le_list_def strict_mono_less_eq)
        with mono_trace_hide[OF aa, of A] ff0 ff1 have "t. trace_hide (f' i) (ev ` A)  f 0 @ t" 
          by (metis (mono_tags, lifting) someI_ex)
      } note zz=this
      {
        define ff' where "ff' = (λi. trace_hide (f' i) (ev ` A))"
        with gg have "mono ff'"
          by (rule_tac monoI, simp add: mono_trace_hide strict_mono_less_eq)
        assume aa:"i. trace_hide (f' i) (ev ` A)  f 0"
        with aa mono_constant have "i. ji. ff' j = ff' i" using mono ff' ff'_def by blast
        then obtain m where bb:"jm. ff' j = ff' m" by blast
        have ff' m  𝒟 (P \ A) 
        proof(simp add:D_Hiding, rule_tac x="f' m" in exI, rule_tac x="[]" in exI, 
              intro conjI, simp, goal_cases)
          case 1
          from gg have "f' m < f' (Suc m)" by (meson lessI strict_monoD)
          moreover from gg obtain k where "f' (Suc m)  ff k" by blast
          moreover have "ff k  𝒯 P" by (metis (mono_tags, lifting) ff0 ff1 someI_ex)
          ultimately show ?case
          by (metis NF_NT append_Nil2 front_tickFree_mono is_processT le_list_def less_list_def)
        next
          case 2
          then show ?case unfolding ff'_def by simp
        next
          case 3
          then show ?case
          proof(rule disjI2, rule_tac x="λi. f' (m + i)" in exI, simp_all, intro conjI allI, goal_cases)
            case 1
            show ?case using gg[THEN conjunct1] 
              by (rule_tac strict_monoI, simp add: strict_monoD) 
          next
            case (2 i)
            from gg obtain k where "f' (m + i)  ff k" by blast
            moreover from ff0 ff1 have "ff k  𝒯 P" by (metis (mono_tags, lifting) someI_ex)
            ultimately have "f' (m + i)  𝒯 P" using is_processT3_ST_pref by blast
            then show ?case by (simp add: add.commute)
          next
            case (3 i)
            then show ?case using bb[THEN spec, of "m+i", simplified] unfolding ff'_def by assumption
          next
            case 4
            then show ?case by (metis Nat.add_0_right rangeI) 
          qed
        qed 
        with gg False have "False"
          by (metis (no_types, lifting) Falsebis aa append_Nil2 ff'_def front_tickFree_mono 
                                        is_processT is_processT2_TR le_list_def) 
      }
      with zz obtain m where hh:"trace_hide (f' m) (ev ` A)  f 0"
        unfolding le_list_def by (metis append_eq_append_conv2)
      from ff0 ff1 gg show ?thesis
      proof(auto simp add:T_Hiding, rule_tac x="f' m" in exI, rule_tac x=u in exI, 
                          intro conjI, simp_all add:3(3), goal_cases)
        case 1
        hence "f' m < f' (Suc m)" by (meson lessI strict_monoD)
        moreover from gg obtain k where "f' (Suc m)  ff k" by blast
        moreover have "ff k  𝒯 P" by (metis (mono_tags, lifting) ff0 ff1 someI_ex)
        ultimately show ?case
          by (metis NF_NT append_Nil2 front_tickFree_mono is_processT le_list_def less_list_def)
      next
        case 2
        from gg obtain k where "f' m  ff k" by blast
        with ff0 ff1 mono_trace_hide[of "f' m"] have "trace_hide (f' m) (ev ` A)  f k" 
          by (metis (mono_tags, lifting) someI_ex)
        with mono_trace_hide[OF this, of B] mono_trace_hide[OF hh, of B] 3(6)[THEN spec, of k] 3(6)
        show ?case by (metis (full_types) dual_order.antisym filter_filter)
      next
        case 3 show ?case 
        proof(rule disjI2, rule_tac x="λi. f' (m + i)" in exI, simp_all, intro conjI allI, goal_cases)
          case 1
          then show ?case by (metis Nat.add_0_right rangeI) 
        next
          case 2 with 3(4) show ?case 
            by (rule_tac strict_monoI, simp add: strict_monoD)
        next
          case (3 i)
          from gg obtain k where "f' (m + i)  ff k" by blast
          moreover from ff0 ff1 have "ff k  𝒯 P" by (metis (mono_tags, lifting) someI_ex)
          ultimately have "f' (m + i)  𝒯 P" using is_processT3_ST_pref by blast
          then show ?case by (simp add: add.commute)
        next
          case (4 i)
          from gg obtain k where "f' (m + i)  ff k" by blast
          with ff0 ff1 mono_trace_hide[of "f' (m + i)"] have ll:"trace_hide (f' (m + i)) (ev ` A)  f k" 
            by (metis (mono_tags, lifting) someI_ex)
          { fix a b c assume "(a::'a event list)  b" and "b  c" and "c  a" hence "b = c" by auto}
          note jj=this
          from jj[OF mono_trace_hide[OF hh, of B],
                  OF mono_trace_hide[THEN mono_trace_hide, of "f' m" "f' (m + i)" B A, 
                               OF gg[THEN conjunct1, THEN strict_mono_mono, 
                               THEN monoD, of "m" "m+i", simplified]]]
               mono_trace_hide[OF ll, of B]
          show ?case unfolding "3a"(6) [THEN spec, of k] by simp
        qed
      qed
    qed
  qed
qed

lemma Hiding_Un_D: finite A  𝒟 ((P \ A) \ B) = 𝒟 (P \ (A  B))
  using Hiding_Un_D1 Hiding_Un_D2 by blast
 
subsection‹ Laws ›

lemma mono_Hiding_FD[simp]: P  Q  P \ A  Q \ A
  apply (auto simp: le_ref_def F_Hiding D_Hiding) 
  using F_subset_imp_T_subset by blast+

lemmas mono_Hiding_ref = mono_Hiding

lemma Hiding_Un: finite A  P \ (A  B) = (P \ A) \ B
proof (simp add:Process_eq_spec, intro conjI, unfold F_Hiding, goal_cases)
  case 1
  thus ?case (is "{(s, X). ?A s X}  {(s, X). ?B s} = 
                  {(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C2  ?C3))}  {(s, X). ?D s}")
  proof(unfold F_Hiding set_eq_subset Un_subset_iff, intro conjI, goal_cases)
    case 1
    then show ?case
      by (auto, metis (no_types) filter_filter image_Un sup_commute sup_left_commute)
  next
    case 2
    then show ?case 
      by (rule_tac Un_mono[of "{}", simplified], insert Hiding_Un_D[of A P B], simp add: D_Hiding)
  next
    case 3
    have "{(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C2))}  {(s, X). ?A s X}" 
      by (auto, metis (no_types) filter_filter image_Un sup_commute sup_left_commute)
    moreover have "{(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C3))}  {(s, X). ?B s}"
    proof(auto,goal_cases)
      case (1 ta u)
      then show ?case using Hiding_fronttickFree by blast
    next
      case (2 u f x)
      then show ?case 
         apply(rule_tac x="f x" in exI, rule_tac x="trace_hide u (ev ` B)" in exI, auto)
         using Hiding_fronttickFree apply blast
        apply(erule_tac x=f in allE) by (metis (no_types) filter_filter rangeI)
    qed
    moreover have "{(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C2  ?C3))} = 
                                  {(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C2 ))}  
                                  {(s, X). (t. (?C1 s t  (t, X  ev ` B)  ?C3))}" by blast 
    ultimately show ?case by (metis (no_types, lifting) Un_mono) 
  next
    case 4
    then show ?case  
      by (rule_tac Un_mono[of "{}", simplified], insert Hiding_Un_D[of A P B], simp add:D_Hiding)
  qed
next
  case 2
  then show ?case by (simp add: Hiding_Un_D)
qed

lemma Hiding_set_BOT: ( \ A) = 
  apply(auto simp add:Process_eq_spec D_Hiding F_Hiding F_UU D_UU)
        using Hiding_fronttickFree apply blast
       using front_tickFree_append Hiding_tickFree apply blast
      using front_tickFree_append Hiding_tickFree apply blast
     apply (metis (full_types) append_Nil filter.simps(1) tickFree_Nil tickFree_implies_front_tickFree)
    using front_tickFree_append Hiding_tickFree apply blast 
   using front_tickFree_append Hiding_tickFree apply blast
  using tickFree_Nil by fastforce 

lemma Hiding_set_STOP: (STOP \ A) = STOP
  apply(auto simp add:Process_eq_spec D_Hiding F_Hiding F_STOP D_STOP T_STOP)
  by (metis (full_types) lessI less_irrefl strict_mono_eq) +

lemma Hiding_set_SKIP: (SKIP \ A) = SKIP 
  apply(auto simp add:Process_eq_spec D_Hiding F_Hiding F_SKIP D_SKIP T_SKIP split:if_splits)
       apply (metis filter.simps(1) non_tickFree_tick)
      apply (metis (full_types) Hiding_tickFree n_not_Suc_n non_tickFree_tick strict_mono_eq)
     apply (metis (full_types) Hiding_tickFree n_not_Suc_n non_tickFree_tick strict_mono_eq)
    apply (metis event.distinct(1) filter.simps(1) imageE)
   apply (metis event.distinct(1) filter.simps(1) filter.simps(2) imageE)
  by (metis (full_types) Hiding_tickFree n_not_Suc_n non_tickFree_tick strict_mono_eq)

lemma Hiding_set_empty: (P \ {}) = P
  apply(auto simp add:Process_eq_spec D_Hiding F_Hiding is_processT7 is_processT8_S strict_mono_eq)
  by (metis append_Nil2 front_tickFree_implies_tickFree front_tickFree_single is_processT 
            nonTickFree_n_frontTickFree)

subsection‹ Multi-Operators laws  ›

lemma Hiding_Ndet: (P  Q) \ A = ((P \ A)  (Q \ A))  
proof(auto simp add:Process_eq_spec D_Hiding F_Hiding, 
      simp_all add: F_Ndet T_Ndet D_Ndet D_Hiding F_Hiding, goal_cases)
  case (1 b t)
  then show ?case by blast
next
  case (2 b t u)
  then show ?case by blast
next
  case (3 b u f x)
  from 3(4) have A:"infinite ({i. f i  𝒯 P})  infinite ({i. f i  𝒯 Q})"
    using finite_nat_set_iff_bounded by auto
  hence "(i. f i  𝒯 P)  (i. f i  𝒯 Q)" 
    by (metis (no_types, lifting) 3(3) finite_nat_set_iff_bounded 
            is_processT3_ST_pref mem_Collect_eq not_less strict_mono_less_eq)
  with A show ?case by (metis (no_types, lifting) 3(1,2,3,5) rangeI)
next
  case (4 a b)
  then show ?case by blast
next
  case (5 t u)
  then show ?case by blast
next
  case (6 u f x)
  from 6(4) have A:"infinite ({i. f i  𝒯 P})  infinite ({i. f i  𝒯 Q})"
    using finite_nat_set_iff_bounded by auto
  hence "(i. f i  𝒯 P)  (i. f i  𝒯 Q)" 
    by (metis (no_types, lifting) 6(3) finite_nat_set_iff_bounded 
            is_processT3_ST_pref mem_Collect_eq not_less strict_mono_less_eq)
  with A show ?case by (metis (no_types, lifting) 6(1,2,3,5) rangeI)
next
  case (7 x)
  then show ?case by blast
qed

lemma Hiding_Mprefix_distr: 
  (B  A) = {}  ((Mprefix A P) \ B) = (Mprefix A (λx. ((P x) \ B)))
proof (auto simp add: Process_eq_spec, 
     simp_all add: F_Mprefix T_Mprefix D_Mprefix D_Hiding F_Hiding,
     goal_cases)
  case (1 x b) then show ?case
  proof(elim exE disjE conjE, goal_cases)
    case (1 t)
    then show ?case by (simp add: inf_sup_distrib2)
  next
    case (2 t a)
    then show ?case 
      by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                    imageE list.sel(1) list.sel(3) list.collapse neq_Nil_conv)
  next
    case (3 t u a)    
    hence "hd t  ev ` B" by force
    with 3 have"x = hd t # trace_hide (tl t) (ev ` B) @ u"
      by (metis append_Cons filter.simps(2) list.exhaust_sel)
    with 3 show ?case by (metis list.distinct(1) list.sel(1) list.sel(3) tickFree_tl) 
  next
    case (4 t u f)
    then obtain k where kk:"t = f k" by blast
    from 4 obtain a where "f 1  []  ev a = hd (f 1)" and aa:"a  A"
      by (metis less_numeral_extra(1) nil_le not_less strict_mono_less_eq) 
    with 4(1) 4(6)[THEN spec, of 0] 4(7)[THEN spec, of 1] have "f 0  []  hd (f 0) = ev a" 
      apply auto 
        apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject 
                                         filter.simps(2) hd_Cons_tl imageE list.distinct(1))
       apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                        hd_Cons_tl imageE list.distinct(1)) 
      by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2)
                                    hd_Cons_tl imageE list.sel(1))
    with 4(1, 7) aa have nf: "i. f i  []  hd (f i) = ev a"    
      by (metis (mono_tags, opaque_lifting) "4"(5) append_Cons le_list_def le_simps(2) list.distinct(1) 
                list.exhaust_sel list.sel(1) neq0_conv old.nat.distinct(1) strict_mono_less_eq) 
    with 4(5) have sm:"strict_mono (tl  f)" by (simp add: less_tail strict_mono_def)
    with 4 aa kk nf show ?case
      apply(rule_tac disjI2, intro conjI) 
        apply (metis (no_types, lifting) Nil_is_append_conv disjoint_iff_not_equal event.inject 
                                          filter.simps(2) hd_Cons_tl imageE list.distinct(1))
       apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                        hd_Cons_tl hd_append2 image_iff list.distinct(1) list.sel(1))
      apply(rule_tac x=a in exI, intro conjI disjI2) 
       apply (metis disjoint_iff_not_equal event.inject filter.simps(2) 
                    hd_Cons_tl hd_append2 image_iff list.distinct(1) list.sel(1))
     apply(rule_tac x="tl t" in exI, rule_tac x="u" in exI, intro conjI, simp_all) 
        apply (metis tickFree_tl)
       apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                        hd_Cons_tl imageE list.distinct(1) list.sel(3) tl_append2)
      apply(subst disj_commute, rule_tac disjCI)
      apply(rule_tac x="tl  f" in exI, intro conjI)
         apply auto         
      apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl list.sel(3))
      done
  qed
next
  case (2 x b)
  then show ?case proof(elim exE disjE conjE, goal_cases)
    case 1 then show ?case 
      apply(rule_tac disjI1, rule_tac x="[]" in exI) 
      by (simp add: disjoint_iff_not_equal inf_sup_distrib2)
  next
    case (2 a t) then show ?case 
      apply(rule_tac disjI1, rule_tac  x="(ev a)#t" in exI) 
      using list.collapse by fastforce
  next
    case (3 a t u)
    then show ?case 
      apply(rule_tac disjI2, rule_tac  x="(ev a)#t" in exI, rule_tac x=u in exI) 
      using list.collapse by fastforce
  next
    case (4 a t u f)
    then show ?case 
      apply(rule_tac disjI2)        
      apply(rule_tac x="(ev a) # t" in exI, rule_tac x="u" in exI, intro conjI, simp)
        apply auto[1]
       using hd_Cons_tl apply fastforce
      apply(rule_tac disjI2, rule_tac x="λi. (ev a) # (f i)" in exI)
      by (auto simp add: less_cons strict_mono_def)
  qed
next
  case (3 x) then show ?case
  proof(elim exE disjE conjE, goal_cases)
    case (1 t u a)
    hence aa: "hd (trace_hide t (ev ` B)) = ev a  trace_hide t (ev ` B)  []"
      by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) hd_Cons_tl 
                                    imageE list.distinct(1) list.sel(1))
    with 1 have  "hd x = ev a  x  []" by simp 
    with 1 show ?case 
      apply(intro conjI, simp_all, rule_tac x=a in exI, simp)
      apply(rule_tac x="tl t" in exI, rule_tac x="u" in exI, intro conjI, simp_all)
       using tickFree_tl apply blast
       using aa by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                          hd_Cons_tl imageE list.sel(3) tl_append2)
  next
    case (2 t u f)
    then obtain k where kk:"t = f k" by blast
    from 2 obtain a where "f 1  []  ev a = hd (f 1)" and aa:"a  A"
      by (metis less_numeral_extra(1) nil_le not_less strict_mono_less_eq) 
    with 2(1) 2(6)[THEN spec, of 0] 2(7)[THEN spec, of 1] have "f 0  []  hd (f 0) = ev a" 
      apply auto 
        apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject 
                                         filter.simps(2) hd_Cons_tl imageE list.distinct(1))
       apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                        hd_Cons_tl imageE list.distinct(1)) 
      by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2)
                                    hd_Cons_tl imageE list.sel(1))
    with 2(1, 7) aa have nf: "i. f i  []  hd (f i) = ev a"    
      by (metis (mono_tags, opaque_lifting) 2(5) append_Cons le_list_def le_simps(2) list.distinct(1) 
                list.exhaust_sel list.sel(1) neq0_conv old.nat.distinct(1) strict_mono_less_eq) 
    with 2(5) have sm:"strict_mono (tl  f)" by (simp add: less_tail strict_mono_def)
    from 2(1,4) nf aa kk have x1:"x  []"
      by (metis Nil_is_append_conv disjoint_iff_not_equal event.inject filter.simps(2) 
                hd_Cons_tl imageE list.distinct(1))
    with 2(1,4) nf aa kk have x2: "hd (trace_hide t (ev ` B)) = ev a  trace_hide t (ev ` B)  []"
      by (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) hd_Cons_tl 
                                    imageE list.distinct(1) list.sel(1))
    with 2(1,4) nf aa kk x1 have x3:"hd x = ev a" by simp    
    with 2 aa kk nf sm x1  show ?case
      apply(intro conjI, simp_all)
     apply(rule_tac x="tl t" in exI, rule_tac x="u" in exI, intro conjI, simp_all) 
        apply (metis tickFree_tl)
       apply (metis (no_types, lifting) disjoint_iff_not_equal event.inject filter.simps(2) 
                                        hd_Cons_tl imageE list.distinct(1) list.sel(3) tl_append2)
      apply(subst disj_commute, rule_tac disjCI)
      apply(rule_tac x="tl  f" in exI, intro conjI)
         apply auto         
       apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl list.sel(3))
      by (metis (no_types, lifting) filter.simps(2) hd_Cons_tl list.sel(3))
  qed
next
  case (4 x) then show ?case
  proof(elim exE disjE conjE, goal_cases)
    case (1 a t u)
    then show ?case
      apply(rule_tac  x="(ev a)#t" in exI, rule_tac x=u in exI) 
      using list.collapse by fastforce
  next
    case (2 a t u f) 
    then show ?case 
      apply(rule_tac x="(ev a) # t" in exI, rule_tac x="u" in exI, intro conjI, simp_all)
        apply auto[1]
       using hd_Cons_tl apply fastforce
      apply(rule_tac disjI2, rule_tac x="λi. (ev a) # (f i)" in exI)
      by (auto simp add: less_cons strict_mono_def)
  qed
qed

lemma no_Hiding_read: (y. c y  B)  ((c?x  (P x)) \ B) = (c?x  ((P x) \ B))
  by (simp add: read_def o_def, subst Hiding_Mprefix_distr, auto)

lemma no_Hiding_write0: a  B  ((a  P) \ B) = (a  (P \ B))
  by (simp add: Hiding_Mprefix_distr write0_def)

lemma Hiding_write0: a  B   ((a  P) \ B) = (P \ B)
proof (auto simp add: write0_def Process_eq_spec, 
       simp_all add: F_Mprefix T_Mprefix D_Mprefix D_Hiding F_Hiding,
       goal_cases)
  case (1 x b)
  then show ?case
    apply(elim exE disjE conjE)
      apply (metis filter.simps(2) hd_Cons_tl image_eqI)
     apply (metis (no_types, lifting) filter.simps(2) image_eqI list.sel(1) 
                                      list.sel(3) neq_Nil_conv tickFree_tl)
  proof(goal_cases)
    case (1 t u f)
    have fS: "strict_mono (f  Suc)" by (metis "1"(5) Suc_mono comp_def strict_mono_def)
    from  1 have aa:"i. f (Suc i)  []"
      by (metis (full_types) less_Suc_eq_le less_irrefl nil_le strict_mono_less_eq)      
    with fS have sm:"strict_mono (tl  f  Suc)" by (simp add: less_tail strict_mono_def)
    with 1 aa show ?case
      apply(subst disj_commute, rule_tac disjCI, simp)        
      apply(rule_tac x="tl (f 1)" in exI, rule_tac x="u" in exI, intro conjI, simp_all) 
        apply (metis Hiding_tickFree imageE tickFree_tl)
      apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl image_eqI rangeE)
      apply(subst disj_commute, rule_tac disjCI)        
      apply(rule_tac x="tl  f  Suc" in exI, intro conjI)
         apply auto
         apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl list.sel(3))
      done
  qed
next
  case (2 aa b)
  then show ?case     
    apply(elim exE disjE conjE)
      apply (metis (no_types, lifting) filter.simps(2) image_eqI list.distinct(1) 
                                        list.sel(1) list.sel(3))
  proof(goal_cases)
    case (1 t u)
    then show ?case by (rule_tac disjI2, rule_tac x="(ev a)#t" in exI, auto)
  next
    case (2 t u f)
    then show ?case
      apply(rule_tac disjI2)         
      apply(rule_tac x="(ev a) # t" in exI, rule_tac x="u" in exI, intro conjI, simp_all)
      apply(rule_tac disjI2)       
      apply(rule_tac x="λi. (ev a) # (f i)" in exI, intro conjI)
      by (auto simp add: less_cons strict_mono_def)
  qed
next
  case (3 x)
  then show ?case 
    apply(elim exE disjE conjE)
     apply(rule_tac x="tl t" in exI, rule_tac x="u" in exI, intro conjI, simp_all)
    using tickFree_tl apply blast
     apply (metis filter.simps(2) hd_Cons_tl image_eqI)
  proof(goal_cases)
    case (1 t u f)
    have fS: "strict_mono (f  Suc)" by (metis "1"(5) Suc_mono comp_def strict_mono_def)
    from  1 have aa:"i. f (Suc i)  []"
      by (metis (full_types) less_Suc_eq_le less_irrefl nil_le strict_mono_less_eq)      
    with fS have sm:"strict_mono (tl  f  Suc)" by (simp add: less_tail strict_mono_def)
    with 1 aa show ?case
      apply(rule_tac x="tl (f 1)" in exI, rule_tac x="u" in exI, intro conjI, simp_all) 
        apply (metis Hiding_tickFree imageE tickFree_tl)
      apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl image_eqI rangeE)
      apply(subst disj_commute, rule_tac disjCI)        
      apply(rule_tac x="tl  f  Suc" in exI, intro conjI)
         apply auto
         apply (metis (no_types, lifting) filter.simps(2) hd_Cons_tl list.sel(3))
      done
  qed
next
  case (4 x)
  then show ?case
    apply(elim exE disjE conjE)
  proof(goal_cases)
    case (1 t u)
    then show ?case by (rule_tac x="(ev a)#t" in exI, auto)
  next
    case (2 t u f)
    then show ?case
      apply(rule_tac x="(ev a) # t" in exI, rule_tac x="u" in exI, intro conjI, simp_all)
      apply(rule_tac disjI2)       
      apply(rule_tac x="λi. (ev a) # (f i)" in exI, intro conjI)
      by (auto simp add: less_cons strict_mono_def)
  qed
qed

lemma no_Hiding_write: (y. c y  B)  ((c!a  P) \ B) = (c!a  (P \ B))
  by(simp add: write_def, subst Hiding_Mprefix_distr, auto)

lemma Hiding_write: (c a)  B  ((c!a  P) \ B) = (P \ B)
  by (simp add: write_def Hiding_write0 Mprefix_singl)


section‹ The Sync Operator Laws ›  

subsection‹ Preliminaries ›

lemma SyncTlEmpty:"a setinterleaves (([], u), A)  tl a setinterleaves (([], tl u), A)"
  by (case_tac u, simp, case_tac a, simp_all split:if_splits)

lemma SyncHd_Tl: 
   "a setinterleaves ((t, u), A)  hd t  A  hd u  A
     hd a = hd u  tl a setinterleaves ((t, tl u), A)"
  by (case_tac u) (case_tac t, auto split:if_splits)+
 
lemma SyncHdAddEmpty: 
   "(tl a) setinterleaves (([], u), A)  hd a  A  a  [] 
     a setinterleaves (([], hd a # u), A)"  
  using hd_Cons_tl by fastforce 

lemma SyncHdAdd: 
  "(tl a) setinterleaves ((t, u), A)  hd a  A  hd t  A  a  [] 
    a setinterleaves ((t, hd a # u), A)" 
  by (case_tac a, simp, case_tac t, auto) 

lemmas SyncHdAdd1 = SyncHdAdd[of "a#r", simplified] for a r

lemma SyncSameHdTl:
  "a setinterleaves ((t, u), A)  hd t  A  hd u  A
    hd t = hd u  hd a = hd t  (tl a) setinterleaves ((tl t, tl u), A)"
  by (case_tac u) (case_tac t, auto split:if_splits)+

lemma SyncSingleHeadAdd: 
   "a setinterleaves ((t, u), A)  h  A
     (h#a) setinterleaves ((h#t, u), A)"
  by (case_tac u, auto split:if_splits)

lemma TickLeftSync:
   "tick  A  front_tickFree t  s setinterleaves (([tick], t), A)  s = t  last t = tick"
proof(induct t arbitrary: s)
  case Nil
  then show ?case by (simp add: Nil.prems)
next
  case (Cons a t)
  then show ?case
    apply (auto split:if_splits)
      using emptyLeftProperty apply blast
     apply (metis last_ConsR last_snoc nonTickFree_n_frontTickFree tickFree_Cons)
    by (metis append_Cons append_Nil front_tickFree_mono)+
qed  
  
lemma EmptyLeftSync:"s setinterleaves (([], t), A)  s = t  set t  A = {}"
  by (meson Int_emptyI emptyLeftNonSync emptyLeftProperty)

lemma tick_T_F:"t@[tick]  𝒯 P  (t@[tick], X)   P"
  using append_T_imp_tickFree is_processT5_S7 by force

lemma event_set: "(e::'a event)  insert tick (range ev)"
  by (metis event.exhaust insert_iff rangeI)

lemma Mprefix_Sync_distr1_D: 
  " A  S 
     B  S 
      𝒟 (Mprefix A P S Mprefix B Q) =  𝒟 ( x   A  B  (P x S Q x))"  
  apply(auto,simp_all add:D_Sync F_Sync F_Mprefix T_Mprefix D_Mprefix)  
   apply(elim exE disjE conjE)  
          apply (metis (no_types, lifting) Sync.sym empty_iff image_iff insertI2 
                       list.exhaust_sel setinterleaving.simps(2) subsetCE)
proof(goal_cases)
  case (1 x t u r v a aa)
  from 1(1,2,6,8,11,13) have aa1: "hd tinsert tick (ev ` S)hd uinsert tick (ev ` S)"   
    by blast
  from 1(5,6,7,8,11,13) aa1 have aa2: " hd x  ev ` (A  B)"  
    by (metis (no_types, lifting) IntI empty_setinterleaving event.inject 
                                  hd_append2 image_iff SyncSameHdTl)
  then show ?case  
    using 1(3,4,5,6,7,9,10,13,14) by (metis (no_types, lifting)  Nil_is_append_conv aa1 
                                            empty_setinterleaving event.inject hd_append2 
                                            SyncSameHdTl tickFree_tl tl_append2)
next
  case (2 x t u r v a)
  then show ?case      
    by (metis (no_types, lifting) Sync.si_empty3 equals0D imageE image_eqI insertI2 list.exhaust_sel subsetCE) 
next
  case (3 x t u r v a aa)
  from 3(1,2,6,8,11,13) have aa1: "hd tinsert tick (ev ` S)hd uinsert tick (ev ` S)"   
    by blast
  from 3(5,6,7,8,11,13) aa1 have aa2: " hd x  ev ` (A  B)"  
    by (metis (no_types, lifting) IntI empty_setinterleaving event.inject hd_append2 image_iff SyncSameHdTl)
  then show ?case 
    using 3(3,4,5,6,7,9,10,13,14) 
    by (metis (no_types, lifting)  Nil_is_append_conv aa1 empty_setinterleaving event.inject 
                                   hd_append2 SyncSameHdTl  tickFree_tl tl_append2) 
next
  case (4 x t u r v a)
  then show ?case        
    by (metis (no_types, lifting) Sync.si_empty3 equals0D imageE image_eqI insertI2 list.exhaust_sel subsetCE)  
next
  case (5 x t u r v a aa)
  from 5(1,2,6,8,11,13) have aa1: "hd tinsert tick (ev ` S)hd uinsert tick (ev ` S)"   
    by blast
  from 5(5,6,7,8,11,13) aa1 have aa2: " hd x  ev ` (A  B)"  
    by (metis (no_types, lifting) IntI empty_setinterleaving event.inject hd_append2 image_iff SyncSameHdTl)
  then show ?case 
    using 5(3,4,5,6,7,9,10,13,14) by (metis  aa1 append_Nil2 empty_setinterleaving event.inject SyncSameHdTl)   
next
  case (6 x t u r v a)
  then show ?case       
    by (metis (no_types, lifting) Sync.si_empty3 equals0D imageE image_eqI insertI2 list.exhaust_sel subsetCE) 
next
  case (7 x t u r v a aa)
  from 7(1,2,6,8,11,13) have aa1: "hd tinsert tick (ev ` S)hd uinsert tick (ev ` S)"   
    by blast
  from 7(5,6,7,8,11,13) aa1 have aa2: " hd x  ev ` (A  B)"  
    by (metis (no_types, lifting) IntI empty_setinterleaving event.inject hd_append2 image_iff SyncSameHdTl)
  then show ?case  
      using 7(3,4,5,6,7,9,10,13,14) by (metis  aa1 append_Nil2 empty_setinterleaving event.inject SyncSameHdTl) 
next
  case (8 x)
  then show ?case 
    apply(elim exE disjE conjE)  
  proof(goal_cases)
    case (1 a t u r v)
    obtain r1 t1 u1 where aa0: "r1=hd x#rt1=hd x#tu1=hd x#u" 
      by auto
    from 1(3,4,5,7,8,9) have aa1: "tickFree r1x = r1 @ v" 
      by (metis  Cons_eq_appendI aa0 event.distinct(1) list.exhaust_sel tickFree_Cons)
    from 1(2,4,9) have aa2: "r1 setinterleaves ((t1, u1), insert tick (ev ` S))t1  []"   
      using aa0 subsetCE by auto
    from 1(4,5,10,11) aa0 
    have aa3: "(tl t1)  𝒟 (P a)  (tl u1)  𝒯 (Q a)  ev a = hd t1  ev a = hd u1  
               hd t1  ev ` A hd u1  ev ` B"  
       by auto
    then show ?case      
      using "1"(6) aa1 aa2 by fastforce 
  next
    case (2 a t u r v)
    obtain r1 t1 u1 where aa0: "r1=hd x#rt1=hd x#tu1=hd x#u" 
      by auto
    from 2(3,4,5,7,8,9) have aa1: "tickFree r1x = r1 @ v" 
      by (metis  Cons_eq_appendI aa0 event.distinct(1) list.exhaust_sel tickFree_Cons)
    from 2(2,4,9) have aa2: "r1 setinterleaves ((t1, u1), insert tick (ev ` S))t1  []"   
      using aa0 subsetCE by auto
    from 2(4,5,10,11) aa0 
    have aa3: "(tl t1)  𝒟 (Q a)  (tl u1)  𝒯 (P a)  ev a = hd t1  ev a = hd u1  
               hd t1  ev ` A hd u1  ev ` B"  
       by auto
    then show ?case      
      using "2"(6) aa1 aa2 by fastforce
  next
    case (3 a t u r v)
    obtain r1 t1 u1 where aa0: "r1=hd x#rt1=hd x#tu1=hd x#u" 
      by auto
    from 3(2,4,9) have aa2: "r1 setinterleaves ((t1, u1), insert tick (ev ` S))t1  []"   
      using aa0 subsetCE by auto
    from 3(3,4,5,7,8,10,11) aa0 
    have aa3: "(tl t1)  𝒟(P a)(tl u1)  𝒯 (Q a) ev a = hd t1ev a = hd u1  
               hd t1  ev ` A hd u1  ev ` Bx = r1 @ v"  
      by (metis (no_types, lifting)  Int_lower1 Int_lower2 append_Nil2 imageE image_eqI 
                                     list.exhaust_sel list.sel(1) list.sel(3) subsetCE)    
    then show ?case   
      by (metis (no_types, lifting) "3"(6) "3"(7) aa2 event.inject imageE)     
  next
    case (4 a t u r v)
    obtain r1 t1 u1 where aa0: "r1=hd x#rt1=hd x#tu1=hd x#u" 
      by auto
    from 4(2,4,9) have aa2: "r1 setinterleaves ((t1, u1), insert tick (ev ` S))t1  []"   
      using aa0 subsetCE by auto
    from 4(3,4,5,7,8,10,11) aa0 
    have aa3: "(tl t1)  𝒟 (Q a)(tl u1)  𝒯 (P a)  ev a = hd t1ev a = hd u1 
               hd t1  ev ` A hd u1  ev ` Bx = r1 @ v"  
      by (metis (no_types, lifting)  Int_lower1 Int_lower2 append_Nil2 imageE image_eqI 
                list.exhaust_sel list.sel(1) list.sel(3) subsetCE)    
    then show ?case   
      by (metis (no_types, lifting) "4"(6) "4"(7) aa2 event.inject imageE)  
  qed
qed

lemma Hiding_interleave: 
  "A  C = {} 
   r setinterleaves ((t, u), C) 
   (trace_hide r A) setinterleaves ((trace_hide t A, trace_hide u A), C)"
proof(induct r arbitrary:t u)
  case Nil
  then show ?case
    using EmptyLeftSync empty_setinterleaving by fastforce
next
  case (Cons a r)
  then show ?case
    apply(cases t) using EmptyLeftSync apply fastforce
    apply(cases u) apply fastforce
  proof(simp split:if_splits, goal_cases)
    case (1 a list lista)
    then show ?case by fastforce
  next
    case (2 a list aa lista)
    then show ?case 
      apply(erule_tac disjE)
       using Cons(1)[of list u] 
       apply (metis (no_types, lifting) filter.simps(2) SyncSingleHeadAdd)
      using Cons(1)[of t lista]
      by (metis (no_types, lifting) Sync.sym filter.simps(2) SyncSingleHeadAdd)
  next
    case (3 a list lista)
    then show ?case by fastforce
  qed
qed

lemma non_Sync_interleaving: 
  "(set t  set u)  C = {}  setinterleaving (t, C, u)  {}" (* FINALLY NON-USED*)
proof(induct t arbitrary:u)
  case Nil
  then show ?case 
    by (metis Un_empty_left disjoint_iff_not_equal emptyLeftSelf empty_iff empty_set)
next
  case (Cons a t)
  then show ?case 
  proof(induct u)
    case Nil
    then show ?case using Sync.sym by auto
  next
    case (Cons a u)
    then show ?case by auto
  qed
qed
  
lemma interleave_Hiding: 
  "A  C = {} 
   ra setinterleaves ((trace_hide t A, trace_hide u A), C) 
   r. ra = trace_hide r A  r setinterleaves ((t, u), C)"
proof(induct "length t + length u" arbitrary:ra t u rule:nat_less_induct)
  case Ind:1
  then show ?case
  proof (cases t)
    case Nilt: Nil
    from Ind(2) have a:"set (trace_hide u A)  C = {}  set u  C = {}" by auto
    hence b: "u setinterleaves ((t, u), C)"
      by (metis (no_types, lifting) Ind(3) EmptyLeftSync Nilt disjoint_iff_not_equal 
                emptyLeftSelf filter.simps(1))
    then show ?thesis 
      apply(rule_tac x=u in exI)
      using EmptyLeftSync[of "ra" C "trace_hide u A"] a b Cons Nilt Ind(3) by auto
  next  
    case Const: (Cons ta tlist)
    then show ?thesis
    proof(cases u)
      case Nilu: Nil
      from Ind(2) have a:"set (trace_hide t A)  C = {}  set t  C = {}" by auto
      hence b: "t setinterleaves ((t, u), C)" 
        by (metis Ind(3) Nilu EmptyLeftSync disjoint_iff_not_equal emptyLeftSelf filter.simps(1) Sync.sym)
      then show ?thesis 
        apply(rule_tac x=t in exI)
        using EmptyLeftSync[of "ra" C "trace_hide t A"] a b Ind Nilu by (metis Sync.sym filter.simps(1))
    next
      case Consu: (Cons ua ulist)
      with Const Ind(2,3) show ?thesis
      proof(auto split:if_splits simp del:setinterleaving.simps, goal_cases)
        case 1
        then show ?case
        proof (auto, goal_cases)
          case (1 raa)
          with Ind(1)[THEN spec, of "length tlist + length u", simplified Const, simplified, 
                        THEN spec, THEN spec, of tlist u, simplified Ind, simplified, 
                        THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((tlist, u), C)" by auto  
          then show ?case using "1"(4) Consu by force
        next
          case (2 raa)
          with Ind(1)[THEN spec, of "length t + length ulist", simplified Consu, simplified, 
                    THEN spec, THEN spec, of t ulist, simplified Ind, simplified, 
                    THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((t, ulist), C)" by auto
          then show ?case using "2"(2) "2"(4) by force
        next
          case (3 raa)
            with Ind(1)[THEN spec, of "length tlist + length ulist", simplified Const Consu, simplified, 
                      THEN spec, THEN spec, of tlist ulist, simplified Ind, simplified, 
                      THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((tlist, ulist), C)" by auto
          then show ?case using "3"(4) by force
        next
          case (4 raa)
          with Ind(1)[THEN spec, of "length t + length ulist", simplified Consu, simplified, 
                    THEN spec, THEN spec, of t ulist, simplified Ind, simplified, 
                    THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((t, ulist), C)" by auto
          then show ?case using "4"(5) Const by force
        next
          case (5 raa)
          with Ind(1)[THEN spec, of "length tlist + length u", simplified Const, simplified, 
                        THEN spec, THEN spec, of tlist u, simplified Ind, simplified, 
                        THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((tlist, u), C)" by auto  
          then show ?case using "5"(4) Consu by force
        next
          case (6 raa)
          with Ind(1)[THEN spec, of "length t + length ulist", simplified Consu, simplified, 
                    THEN spec, THEN spec, of t ulist, simplified Ind, simplified, 
                    THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((t, ulist), C)" by auto
          then show ?case using "6"(5) Const by force
        next
          case (7 raa)
          with Ind(1)[THEN spec, of "length tlist + length u", simplified Const, simplified, 
                        THEN spec, THEN spec, of tlist u, simplified Ind, simplified, 
                        THEN spec, of raa] obtain r where 
            "raa = trace_hide r A  r setinterleaves ((tlist, u), C)" by auto  
          then show ?case using "7"(4) Consu by force
        qed
      next
        case 2
        with Ind(1)[THEN spec, of "length t + length ulist", simplified Consu, simplified, 
                      THEN spec, THEN spec, of t ulist, simplified Ind, simplified, 
                      THEN spec, of ra] obtain r where 
          "ra = trace_hide r A  r setinterleaves ((t, ulist), C)" by auto   
        then show ?case 
          apply(rule_tac x="ua#r" in exI)
          using "2"(5) Const Ind.prems(1) by auto
      next
        case 3
        with Ind(1)[THEN spec, of "length tlist + length u", simplified Const, simplified, 
                      THEN spec, THEN spec, of tlist u, simplified Ind, simplified, 
                      THEN spec, of ra] obtain r where 
          "ra = trace_hide r A  r setinterleaves ((tlist, u), C)" by auto   
        then show ?case
          apply(rule_tac x="ta#r" in exI)
          using "3"(4) Consu Ind.prems(1) by auto
      next
        case 4
        with Ind(1)[THEN spec, of "length tlist + length ulist", simplified Const Consu, simplified, 
                      THEN spec, THEN spec, of tlist ulist, simplified Ind, simplified, 
                      THEN spec, of ra] obtain r where 
          "ra = trace_hide r A  r setinterleaves ((tlist, ulist), C)" by auto
        then show ?case
          apply(rule_tac x="ta#ua#r" in exI)
          using "4"(4,5) Consu Const Ind.prems(1) apply auto
           using SyncSingleHeadAdd apply blast 
          by (metis Sync.sym SyncSingleHeadAdd)
      qed
    qed
  qed
qed

lemma interleave_size: 
  "s setinterleaves ((t,u), C)  length s = length t + length u - length(filter (λx. xC) t)"
proof(induct s arbitrary:t u)
  case Nil
  then show ?case using EmptyLeftSync empty_setinterleaving by fastforce
next
  case (Cons a list)
  then show ?case
    apply(cases t) using emptyLeftProperty apply fastforce
    apply(cases u) 
     apply (metis (no_types, lifting) Sync.sym add_diff_cancel_right' emptyLeftNonSync 
                  emptyLeftProperty filter_empty_conv)
    proof(auto split:if_splits, goal_cases 11 12 13 14 15)
      case (11 tlist ulist)
      then show ?case 
        by (metis (no_types, lifting) Suc_diff_le le_add1 length_filter_le order_trans)
    next
      case (12 ta tlist ulist)
      with 12(3)[rule_format, of "ta#tlist" ulist] show ?case 
        by simp (metis Suc_diff_le le_add1 length_filter_le order_trans)
    next
      case (13 tlist ua ulist)
      with 13(3)[rule_format, of tlist "ua#ulist"] show ?case 
        by simp (metis Suc_diff_le le_less_trans length_filter_le less_SucI less_Suc_eq_le less_add_Suc1)
    next
      case (14 ta tlist ulist)
      with 14(3)[rule_format, of "ta#tlist" ulist] show ?case 
        by simp (metis Suc_diff_le le_less_trans length_filter_le less_SucI less_Suc_eq_le less_add_Suc1)
    next
      case (15 tlist ua ulist)
      with 15(3)[rule_format, of tlist "ua#ulist"] show ?case
        by simp (metis Suc_diff_le le_less_trans length_filter_le less_SucI less_Suc_eq_le less_add_Suc1)
    qed
qed 

lemma interleave_eq_size: 
  "s setinterleaves ((t,u), C)  s' setinterleaves ((t,u), C)  length s = length s'"
  by (simp add: interleave_size)

lemma interleave_set: "s setinterleaves ((t,u), C)  set t  set u  set s"
proof(induct s arbitrary: t u)
  case Nil
  then show ?case using EmptyLeftSync empty_setinterleaving by blast
next
  case (Cons a s)
  then show ?case
    apply(cases t) using emptyLeftProperty apply fastforce
    apply(cases u) apply (metis Sync.sym Un_empty_right emptyLeftProperty empty_set eq_refl)
    by (auto simp add: subset_iff split:if_splits) 
qed 

lemma interleave_order: "s setinterleaves ((t1@t2,u), C)  set(t2)  set(drop (length t1) s)"
proof(induct s arbitrary: t1 t2 u)
  case Nil
  then show ?case using empty_setinterleaving by auto
next
  case (Cons a s)
  then show ?case
  apply(cases t1) using append_self_conv2 interleave_set apply fastforce
  apply(cases u) apply (metis EmptyLeftSync Sync.sym append_eq_conv_conj order_refl) 
  proof (auto simp add: subset_iff split:if_splits, goal_cases)
    case (1 a list lista t)
    then show ?case using Cons(1)[of "a#list" "t2" "lista", simplified, OF 1(6)]
      by (meson Suc_n_not_le_n contra_subsetD nat_le_linear set_drop_subset_set_drop)
  next
    case (2 a list lista t)
    then show ?case using Cons(1)[of "a#list" "t2" "lista", simplified, OF 2(7)]
      by (meson Suc_n_not_le_n contra_subsetD nat_le_linear set_drop_subset_set_drop)
  qed
qed 

lemma interleave_append: 
  "s setinterleaves ((t1@t2,u), C) 
     u1 u2 s1 s2. u = u1@u2  s = s1@s2  
                      s1 setinterleaves ((t1,u1), C)  s2 setinterleaves ((t2,u2), C)"
proof(induct s arbitrary: t1 t2 u)
  case Nil
  then show ?case using empty_setinterleaving by fastforce
next
  case (Cons a s)
  then show ?case
  apply(cases t1) using append_self_conv2 interleave_set apply fastforce
  apply(cases u) apply(exI "[]", exI "[]") apply auto[1]
    apply (metis (no_types, opaque_lifting) Nil_is_append_conv append_Cons)
  proof (auto simp add: subset_iff split:if_splits, goal_cases)
    case (1 list lista)
    with Cons(1)[of "list" "t2" "lista", simplified, OF 1(5)] show ?case
    proof(elim exE conjE, goal_cases)
      case (1 u1 u2 s1 s2)
      then show ?case 
        by (exI "a#u1", exI "u2", simp) (metis append_Cons)
    qed      
  next
    case (2 aa list lista)
    with Cons(1)[of "aa#list" "t2" "lista", simplified, OF 2(6)] show ?case
    proof(elim exE conjE, goal_cases)
      case (1 u1 u2 s1 s2)
      then show ?case 
        by (exI "a#u1", exI "u2", simp) (metis append_Cons)
    qed  
  next
    case (3 list aa lista)
    with Cons(1)[of "list" "t2" "aa#lista", simplified, OF 3(6)] show ?case
    proof(elim exE conjE, goal_cases)
      case (1 u1 u2 s1 s2)
      then show ?case 
        apply (exI "u1", exI "u2", simp) by (metis append_Cons SyncSingleHeadAdd)
    qed  
  next
    case (4 aa list lista)
    with Cons(1)[of "aa#list" "t2" "lista", simplified, OF 4(6)] show ?case
    proof(elim exE conjE, goal_cases)
      case (1 u1 u2 s1 s2)
      then show ?case 
        by (exI "a#u1", exI "u2", simp) (metis append_Cons)
    qed 
  next
    case (5 list aa lista)
    with Cons(1)[of "list" "t2" "aa#lista", simplified, OF 5(6)] show ?case
    proof(elim exE conjE, goal_cases)
      case (1 u1 u2 s1 s2)
      then show ?case 
        apply (exI "u1", exI "u2", simp) by (metis append_Cons SyncSingleHeadAdd)
    qed
  qed
qed 

lemma interleave_append_sym: 
  "s setinterleaves ((t,u1@u2), C) 
     t1 t2 s1 s2. t = t1@t2  s = s1@s2  
                      s1 setinterleaves ((t1,u1), C)  s2 setinterleaves ((t2,u2), C)"
  by (metis (no_types) Sync.sym interleave_append)

lemma interleave_append_tail: 
  "s setinterleaves ((t1,u), C)  (set t2)  C = {}  (s@t2) setinterleaves ((t1@t2,u), C)"
proof(induct s arbitrary: t1 t2 u)
  case Nil
  then show ?case by (metis Set.set_insert Sync.sym append_Nil disjoint_insert(2) 
                            emptyLeftSelf empty_setinterleaving)
next
  case (Cons a s)
  then show ?case
    apply(cases u) using EmptyLeftSync Sync.sym apply fastforce 
    apply(cases t1, cases t2) apply simp apply fastforce 
  proof(auto, goal_cases)
    case (1 list lista)
    with 1(1)[OF 1(7) 1(2)] show ?case by simp
  next
    case (2 list aa lista)
    with 2(1)[OF 2(2)] show ?case by simp  
  next
    case (3 list aa lista)
    with 3(1)[OF 3(9) 3(2)] show ?case by simp
  next
    case (4 list aa lista)
    with 4(1)[OF 4(9) 4(2)] show ?case by simp
  qed
qed

lemma interleave_append_tail_sym: 
  "s setinterleaves ((t,u1), C)  (set u2)  C = {}  (s@u2) setinterleaves ((t,u1@u2), C)"
  by (metis (no_types) Sync.sym interleave_append_tail)

lemma interleave_assoc_1: 
  "tu setinterleaves ((t, u), A) 
    tuv setinterleaves ((tu, v), A) 
    uv. uv setinterleaves ((u, v), A)  tuv setinterleaves ((t, uv), A)"
proof(induct tuv arbitrary: t tu u v)
  case Nil
  then show ?case using EmptyLeftSync empty_setinterleaving by blast
next
  case Cons_tuv:(Cons a tuv)
  then show ?case
  proof(cases t)
    case Nil_t:Nil
    with Cons_tuv(2) have *:"tu = u" using EmptyLeftSync by blast
    show ?thesis
    proof(cases u)
      case Nil_u:Nil
      with Nil_t Cons_tuv show ?thesis using EmptyLeftSync by fastforce
    next
      case Cons_u:(Cons ua ulist)
      with Nil_t Cons_tuv(2) have "ua  A" by force  
      show ?thesis 
      proof(cases v)
        case Nil_v:Nil
        with * Nil_t Cons_tuv(2,3) Cons_u show ?thesis using Sync.sym by blast
      next
        case Cons_v:(Cons va vlist)
        with * Nil_t Cons_tuv(2,3) Cons_u show ?thesis apply(exI "a#tuv", auto split:if_splits) 
          using Cons_tuv.hyps Cons_tuv.prems(1) emptyLeftProperty by blast+
      qed
    qed
  next
    case Cons_t:(Cons ta tlist)
    show ?thesis
    proof(cases u)
      case Nil_u:Nil
      with Cons_t Cons_tuv show ?thesis
        by (metis Sync.sym emptyLeftProperty emptyLeftSelf empty_set equals0D ftf_Sync21)
    next
      case Cons_u:(Cons ua ulist)
      show ?thesis 
      proof(cases v)
        case Nil_v:Nil
        with Cons_tuv(3) have "a # tuv = tu" by (simp add: Nil_v EmptyLeftSync Sync.sym)
        with Nil_v Cons_u Cons_t Cons_tuv show ?thesis apply(exI u, auto split:if_splits)
           apply (metis Cons_t Nil_v Sync.sym emptyLeftNonSync list.set_intros(1))
          using Cons_tuv(1)[of tuv tlist u] 
            apply(metis (no_types, lifting) Sync.sym emptyLeftNonSync emptyLeftSelf list.sel(3) SyncTlEmpty)
        by (metis Cons_t Sync.sym emptyLeftProperty) fastforce+  
      next
        case Cons_v:(Cons va vlist)
        with Cons_t Cons_u Cons_tuv(2,3) show ?thesis 
        proof(auto split:if_splits, goal_cases)
          case (1 tulist)
          from Cons_tuv(1)[OF 1(5) 1(10)] obtain uvlist 
            where "  uvlist setinterleaves ((ulist, vlist), A) 
                    tuv setinterleaves ((tlist, uvlist), A)" by blast
          with 1 show ?case by(exI "va#uvlist", simp)
        next
          case (2 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (3 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd) 
        next
          case (4 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (5 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (6 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (7 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (8 tulist)
          from Cons_tuv(1)[OF 8(5) 8(9)] obtain uvlist 
            where "uvlist setinterleaves ((va#ulist, va#vlist), A)  
                   tuv setinterleaves ((tlist, uvlist), A)" by blast
          with 8 show ?case using SyncSingleHeadAdd by (exI "uvlist", simp) blast
        next
          case (9 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (10 tulist)
          from Cons_tuv(1)[OF 10(6) 10(10)] obtain uvlist 
            where "uvlist setinterleaves ((ua#ulist, va#vlist), A)  
                   tuv setinterleaves ((tlist, uvlist), A)" by blast
          with 10 show ?case using SyncSingleHeadAdd by (exI "uvlist", simp) blast
        next
          case (11 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (12 u)
          then show ?case using Cons_tuv.hyps by fastforce
        next
          case (13 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (14 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (15 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (16 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (17 u)
          then show ?case by (metis Cons_tuv.hyps Sync.sym SyncSingleHeadAdd)
        next
          case (18 u)
          then show ?case using Cons_tuv.hyps by fastforce
        next
          case (19 u)
          then show ?case using Cons_tuv.hyps by fastforce
        next
          case (20 u)
          then show ?case by (metis Cons_tuv.hyps Cons_tuv.prems(1) Sync.sym SyncSingleHeadAdd)
        next
          case (21 u)
          then show ?case using Cons_tuv.hyps by fastforce
        qed
      qed
    qed
  qed 
qed

lemma interleave_assoc_2:
  assumes  *:"uv setinterleaves ((u, v), A)" and 
         **:"tuv setinterleaves ((t, uv), A)"
  shows "tu. tu setinterleaves ((t, u), A)  tuv setinterleaves ((tu, v), A)"
  using "*" "**" Sync.sym interleave_assoc_1 by blast

subsection‹ Laws ›

lemma Sync_commute: "(P  S  Q) = (Q  S  P)"
  by (simp add: Process_eq_spec mono_D_Sync mono_F_Sync)

lemma mono_Sync_FD_oneside[simp]: "P  P'  (P  S  Q)  (P'  S  Q)"
  apply(auto simp:le_ref_def F_Sync D_Sync) 
  using F_subset_imp_T_subset front_tickFree_Nil by blast+

lemma mono_Sync_FD[simp]: "P  P'; Q  Q'  (P  S  Q)  (P'  S  Q')"
  using mono_Sync_FD_oneside[of P P' S Q] mono_Sync_FD_oneside[of Q Q' S P]
  by (simp add: order_trans Sync_commute)

lemma mono_Sync_ref: "P  P'; Q  Q'  (P  S  Q)  (P'  S  Q')"
  using mono_Sync_sym[of Q Q' P S] mono_Sync[of P P' S Q'] below_trans by blast

lemma Sync_BOT: "(P  S  ) = "
  apply(auto simp add:Process_eq_spec, simp_all add:D_Sync F_Sync F_UU D_UU)
     apply (metis D_imp_front_tickFree append_Nil2 front_tickFree_append ftf_Sync is_processT is_processT2_TR)
    apply (metis Nil_elem_T Sync.si_empty1 append_Nil front_tickFree_Nil insertI1 non_tickFree_implies_nonMt)
   apply (metis D_imp_front_tickFree append_Nil2 front_tickFree_append ftf_Sync is_processT2_TR)
  by (metis Nil_elem_T Sync.si_empty1 append_Nil front_tickFree_Nil insertI1 non_tickFree_implies_nonMt)

lemma Sync_SKIP_SKIP: "(SKIP  S  SKIP) = SKIP"
  apply(auto simp add:Process_eq_spec, simp_all add:D_Sync F_Sync F_SKIP D_SKIP)
  apply(elim exE conjE disjE, auto)
   apply (metis Sync.si_empty1 inf.idem insertI1 sup_commute sup_inf_absorb)
  apply(exI "[tick]", exI "[tick]", simp) 
  by blast

lemma Sync_SKIP_STOP: "(SKIP S STOP) = STOP"
proof(auto simp add:Process_eq_spec, simp_all add:D_Sync F_Sync F_SKIP D_SKIP F_STOP D_STOP, goal_cases)
  case (1 a b)
  then show ?case by (elim exE conjE disjE, auto)
next
  case (2 a b)
  then show ?case
    apply(rule_tac x="[]" in exI, simp, rule_tac x="b-{tick}" in exI, simp, rule_tac x="b" in exI) 
    by blast  
qed



subsection‹ Multi-Operators laws  ›

lemma Mprefix_Sync_distr:
  ( x  A  A'  P x)  S  ( y  B  B'  Q y) =     
   ( x  A        (                 P x   S  ( y  B  B'  Q y))) 
   ( y  B        (( x  A  A'  P x)  S                   Q y))   
   ( x  A'  B'  (                 P x   S                   Q x))
  (is ?lhs A A' P B B' Q = ?rhs A A' P B B' Q) 
  if sets_assms: A  S = {} A'  S B  S = {} B'  S
  (* new proof by Benoît Ballenghien *)
proof (subst Process_eq_spec_optimized, safe)
  fix s X
  assume (s, X)   (?lhs A A' P B B' Q)
     and same_div : 𝒟 (?lhs A A' P B B' Q) = 𝒟 (?rhs A A' P B B' Q)
  from this(1) consider 
    s_P s_Q X_P X_Q. (s_P, X_P)   (Mprefix (A  A') P) 
                       (s_Q, X_Q)   (Mprefix (B  B') Q) 
                       s setinterleaves ((s_P, s_Q), insert tick (ev ` S))  
                       X = (X_P  X_Q)  insert tick (ev ` S)  X_P  X_Q
    | s  𝒟 (?lhs A A' P B B' Q)
    by (simp add: F_Sync D_Sync) blast
  thus (s, X)   (?rhs A A' P B B' Q)
  proof cases
    case 1
    then obtain s_P s_Q X_P X_Q 
      where * : (s_P, X_P)   (Mprefix (A  A') P) (s_Q, X_Q)   (Mprefix (B  B') Q)
                s setinterleaves ((s_P, s_Q), insert tick (ev ` S))
                X = (X_P  X_Q)  insert tick (ev ` S)  X_P  X_Q by blast
    thus (s, X)   (?rhs A A' P B B' Q)
    proof (cases s = []  hd s = tick)
      case True
      with *(1, 2, 3) have ** : s = []  s_P = []  s_Q = []
        by (cases s_P; cases s_Q; force simp add: F_Mprefix subset_iff split: if_split_asm)
      with *(1, 2, 4) sets_assms(1, 3) show (s, X)   (?rhs A A' P B B' Q)
        by (auto simp add: subset_iff F_Det D_Det T_Det F_Mprefix image_Un)[1]
    next
      case False
      then obtain e where *** : s  [] hd s = ev e by (meson event.exhaust)
      from *(1, 2, 3) *** sets_assms consider
        e  A  s_P  []  hd s_P = ev e  (tl s_P, X_P)   (P e)  
         tl s setinterleaves ((tl s_P, s_Q), insert tick (ev ` S)) | 
        e  B  s_Q  []  hd s_Q = ev e  (tl s_Q, X_Q)   (Q e)  
         tl s setinterleaves ((s_P, tl s_Q), insert tick (ev ` S)) | 
        e  A'  e  B'  s_P  []  s_Q  []  hd s_P = ev e  hd s_Q = ev e  (tl s_P, X_P)   (P e)  
         (tl s_Q, X_Q)   (Q e)  tl s setinterleaves ((tl s_P, tl s_Q), insert tick (ev ` S))
        by (cases s_P; cases s_Q; auto simp add: F_Mprefix split: if_split_asm)
      thus (s, X)   (?rhs A A' P B B' Q)
        apply cases
          apply (simp_all add: F_Det ***(1))
          apply (rule disjI1, simp add: F_Mprefix ***, simp add: F_Sync, rule disjI1)
          apply (rule_tac x = tl s_P in exI, rule_tac x = s_Q in exI, rule_tac x = X_P in exI,
                 simp, rule_tac x = X_Q in exI, simp add: *(2, 4))
          apply (rule disjI2, rule disjI1, simp add: F_Mprefix ***, simp add: F_Sync, rule disjI1)
         apply (rule_tac x = s_P in exI, rule_tac x = tl s_Q in exI, rule_tac x = X_P in exI,
                simp add: *(1), rule_tac x = X_Q in exI, simp add: *(4))
        apply (rule disjI2, rule disjI2, simp add: F_Mprefix *** F_Sync, rule disjI1)
        by (rule_tac x = tl s_P in exI, rule_tac x = tl s_Q in exI, rule_tac x = X_P in exI, 
            simp, rule_tac x = X_Q in exI, simp add: *(4))
    qed
  next
    show s  𝒟 (?lhs A A' P B B' Q)  (s, X)   (?rhs A A' P B B' Q) 
      using same_div NF_ND by blast
  qed
next
  
  fix s X
  { fix P Q A A' B B'
    assume assms : s  [] (s, X)   (x  A  (P x S Mprefix (B  B') Q))
                   A  S = {} A'  S B  S = {} B'  S
       and same_div : 𝒟 (?lhs A A' P B B' Q) = 𝒟 (?rhs A A' P B B' Q)
    from assms(1, 2) obtain e 
      where * : e  A hd s = ev e (tl s, X)   (P e S Mprefix (B  B') Q)
      by (auto simp add: F_Mprefix)
    from "*" assms(1) consider 
        s_P s_Q X_P X_Q. (s_P, X_P)   (P e)  (s_Q, X_Q)   (Mprefix (B  B') Q)  
         tl s setinterleaves ((s_P, s_Q), ev ` S  {tick})  X = (X_P  X_Q)  (ev ` S  {tick})  X_P  X_Q
        | s  𝒟 (x  A  (P x S Mprefix (B  B') Q)) 
      by (force simp add: F_Sync D_Mprefix D_Sync)
    hence (s, X)   (?lhs A A' P B B' Q)
    proof cases
      case 1
      then obtain s_P s_Q X_P X_Q 
        where ** : (s_P, X_P)   (P e) (s_Q, X_Q)   (Mprefix (B  B') Q) 
                   tl s setinterleaves ((s_P, s_Q), ev ` S  {tick}) 
                   X = (X_P  X_Q)  (ev ` S  {tick})  X_P  X_Q by blast
      show (s, X)   (?lhs A A' P B B' Q)
        apply (simp add: F_Sync, rule disjI1)
        apply (rule_tac x = ev e # s_P in exI, rule_tac x = s_Q in exI,
               rule_tac x = X_P in exI, intro conjI)
         apply (simp add: F_Mprefix image_iff "*"(1) "**"(1))
        apply (rule_tac x = X_Q in exI, simp add: "**"(2, 4))
        apply (subst list.collapse[OF assms(1), symmetric])
        using "*"(1, 2) "**"(3) assms(3) by (cases s_Q) auto 
    next
      assume s  𝒟 (xA  (P x S Mprefix (B  B') Q))
      hence s  𝒟 (?lhs A A' P B B' Q) by (simp add: same_div D_Det)
      thus (s, X)   (?lhs A A' P B B' Q) using NF_ND by blast
    qed
  } note * = this

  { assume assms : s  [] (s, X)   (xA'  B'  (P x S Q x))
       and same_div : 𝒟 (?lhs A A' P B B' Q) = 𝒟 (?rhs A A' P B B' Q)
    then obtain e where * : e  A' e  B' hd s = ev e (tl s, X)   (P e S Q e)
      by (auto simp add: F_Mprefix)
    have inside: e  S using "*"(2) that(4) by blast
    from "*" assms(1) consider 
        s_P s_Q X_P X_Q. (s_P, X_P)   (P e)  (s_Q, X_Q)   (Q e) 
         tl s setinterleaves ((s_P, s_Q), ev ` S  {tick}) 
         X = (X_P  X_Q)  (ev ` S  {tick})  X_P  X_Q
        | s  𝒟 (xA'  B'  (P x S Q x))
      by (force simp add: F_Sync D_Mprefix D_Sync)
    hence (s, X)   (?lhs A A' P B B' Q)
    proof cases
      case 1
      then obtain s_P s_Q X_P X_Q 
        where ** : (s_P, X_P)   (P e) (s_Q, X_Q)   (Q e) 
                   tl s setinterleaves ((s_P, s_Q), ev ` S  {tick}) 
                   X = (X_P  X_Q)  (ev ` S  {tick})  X_P  X_Q by blast
      show (s, X)   (?lhs A A' P B B' Q)
        apply (subst list.collapse[OF assms(1), symmetric], simp add: F_Sync "*"(3), rule disjI1)
        apply (rule_tac x = ev e # s_P in exI, rule_tac x = ev e # s_Q in exI)
        apply (rule_tac x = X_P in exI, intro conjI, simp add: F_Mprefix "*"(1) "**"(1))
        using "**"(3) by (rule_tac x = X_Q in exI) (simp add: "*"(2) "**"(2, 4) inside F_Mprefix)
    next
      assume s  𝒟 (xA'  B'  (P x S Q x))
      hence s  𝒟 (?lhs A A' P B B' Q) by (simp add: same_div D_Det)
      thus (s, X)   (?lhs A A' P B B' Q) using NF_ND by blast
    qed
  } note ** = this
  
  have *** : X  ev ` (A'  B') = {}  X  ev ` A = {}  X  ev ` B = {}  
              ([], X)   (?lhs A A' P B B' Q)
    apply (simp add: F_Sync, rule disjI1)
    apply (rule_tac x = [] in exI, rule_tac x = [] in exI, simp add: F_Mprefix)
    apply (rule_tac x = X - (ev ` (A' - B')) in exI, intro conjI, fastforce)
    apply (rule_tac x = X - (ev ` (B' - A')) in exI, intro conjI, fastforce)
    using sets_assms(2, 4) by auto

  assume same_div : 𝒟 (?lhs A A' P B B' Q) = 𝒟 (?rhs A A' P B B' Q)
  hence same_div_sym : 𝒟 (?lhs B B' Q A A' P) = 𝒟 (?rhs B B' Q A A' P)
    by (subst Sync_commute, subst Int_commute, subst Det_commute, simp add: Sync_commute)
  show (s, X)   (?rhs A A' P B B' Q)  (s, X)   (?lhs A A' P B B' Q)
    apply (auto simp add: F_Det)
         apply (rule "***"; simp add: F_Mprefix)
        apply (rule "*"; simp add: sets_assms same_div)
       apply (subst (asm) Sync_commute, subst Sync_commute)
       apply (rule "*"; simp add: sets_assms same_div_sym)
      apply (erule "**", assumption, rule same_div)
     apply (simp add: D_Mprefix D_Det)[1]
    by (simp add: T_Mprefix T_Det)
next

  { fix s t u r v P Q A A' B B'
    assume assms : front_tickFree v tickFree r  v = [] s = r @ v 
                   r setinterleaves ((t, u), insert tick (ev ` S)) 
                   t  𝒟 (Mprefix (A  A') P) u  𝒯 (Mprefix (B  B') Q)
                   A  S = {} A'  S B  S = {} B'  S
    from assms(5) obtain e where * : t  [] hd t = ev e tl t  𝒟 (P e) e  A  e  A'
      by (force simp add: D_Mprefix)
    have nonNil: r  []  s  []
      using *(1) assms(3, 4) empty_setinterleaving by blast
    have s  𝒟 (?rhs A A' P B B' Q)
    proof (cases u = [])
      case True
      hence hd s = ev e by (metis "*"(2) EmptyLeftSync Sync.sym assms(3, 4) hd_append nonNil)
      also from "*"(1, 2, 4) Sync.sym assms(4, 8)[simplified True] have e  A 
        using emptyLeftNonSync hd_in_set by fastforce
      ultimately show s  𝒟 (?rhs A A' P B B' Q)
        apply (simp add: D_Det)
        apply (rule disjI1, simp add: D_Mprefix nonNil D_Sync)
        apply (rule_tac x = tl t in exI, rule_tac x = [] in exI,
               rule_tac x = tl r in exI, rule_tac x = v in exI)
        apply (auto simp add: assms(1, 3, 6)[simplified True] * nonNil)[1]
         apply (metis assms(2) tickFree_tl)
        using Sync.sym SyncTlEmpty True assms(4) by blast
    next
      case False
      with assms(6) obtain e' where ** : hd u = ev e' tl u  𝒯 (Q e') e'  B  e'  B'
        by (auto simp add: T_Mprefix)
      consider e   A  hd s = ev e   tl r setinterleaves ((tl t, u), insert tick (ev ` S)) | 
               e'  B  hd s = ev e'  tl r setinterleaves ((t, tl u), insert tick (ev ` S)) | 
               e = e'  e  A'  e  B'  hd s = ev e  
                tl r setinterleaves ((tl t, tl u), insert tick (ev ` S))
        using assms(4) 
        apply (subst (asm) list.collapse[OF nonNil[THEN conjunct1], symmetric],
               subst (asm) list.collapse[OF *(1), symmetric, simplified *(2)],
               subst (asm) list.collapse[OF False, symmetric, simplified **(1)])
        apply (simp add: assms(3) nonNil image_iff split: if_split_asm)
           apply (metis (no_types, opaque_lifting) *(4) **(3) Int_iff 
                        assms(7, 9) empty_iff list.sel(1, 3))
          apply (metis (no_types, opaque_lifting) *(1, 2) **(3) Int_iff 
                       assms(10) inf.order_iff list.exhaust_sel list.sel(1, 3))
         apply (metis (no_types, opaque_lifting) *(1, 2, 4) **(1, 3) Int_iff
                      False assms(8, 10) inf.order_iff list.exhaust_sel list.sel(1, 3))
        by (metis (no_types, opaque_lifting) *(4) **(1) False assms(8) 
                  list.collapse list.sel(1, 3) subsetD)
      thus s  𝒟 (?rhs A A' P B B' Q)
        apply cases
          apply (simp_all add: D_Det)
          apply (rule disjI1, simp add: D_Mprefix nonNil D_Sync)
          apply (rule_tac x = tl t in exI, rule_tac x = u in exI,
                 rule_tac x = tl r in exI, rule_tac x = v in exI)
          apply (simp add: assms(1, 3, 6) *(3) nonNil, use assms(2) nonNil tickFree_tl in blast)
         apply (rule disjI2, rule disjI1, simp add: D_Mprefix nonNil D_Sync)
         apply (rule_tac x = t in exI, rule_tac x = tl u in exI,
                rule_tac x = tl r in exI, rule_tac x = v in exI)
         apply (simp add: assms(1, 3, 5) **(2) nonNil,
                metis "*" UnCI assms(2) image_eqI tickFree_tl)
        apply (rule disjI2, rule disjI2, auto simp add: D_Mprefix nonNil image_iff)
        apply (simp add: D_Sync)
        apply (rule_tac x = tl t in exI, rule_tac x = tl u in exI,
               rule_tac x = tl r in exI, rule_tac x = v in exI)
        by (use *(3) **(2) assms(1, 2, 3) nonNil tickFree_tl in auto simp add: nonNil)
    qed
  } note * = this

  fix s
  assume s  𝒟 (?lhs A A' P B B' Q)
  then obtain t u r v
    where ** : front_tickFree v tickFree r  v = [] s = r @ v 
               r setinterleaves ((t, u), insert tick (ev ` S)) 
               t  𝒟 (Mprefix (A  A') P)  u  𝒯 (Mprefix (B  B') Q) 
                t  𝒟 (Mprefix (B  B') Q)  u  𝒯 (Mprefix (A  A') P) 
    by (simp add: D_Sync) blast
  have same_div : 𝒟 (?rhs A A' P B B' Q) = 𝒟 (?rhs B B' Q A A' P)
    by (subst Det_commute, subst Int_commute, simp add: Sync_commute)
  from **(5) show s  𝒟 (?rhs A A' P B B' Q)
    apply (rule disjE)
    by (rule *[OF **(1, 2, 3, 4)]; simp add: sets_assms)
       (subst same_div, rule *[OF **(1, 2, 3, 4)]; simp add: sets_assms)
next

  { fix A A' B B' P Q s
    assume set_assm : A  S = {}
    have s  𝒟 (xA  (P x S Mprefix (B  B') Q))  s  𝒟 (?lhs A A' P B B' Q)
    proof (auto simp add: D_Mprefix)
      fix e
      assume assms: s  [] hd s = ev e e  A tl s  𝒟 (P e S Mprefix (B  B') Q)
      from assms(4) obtain t u r v 
        where * : front_tickFree v tickFree r  v = [] tl s = r @ v
                  r setinterleaves ((t, u), insert tick (ev ` S))
                  t  𝒟 (P e)  u  𝒯 (Mprefix (B  B') Q)  
                   t  𝒟 (Mprefix (B  B') Q)  u  𝒯 (P e) by (simp add: D_Sync) blast
      have notin: e  S using assms(3) set_assm by blast
      show s  𝒟 (?lhs A A' P B B' Q)
        apply (subst list.collapse[OF assms(1), symmetric], simp add: D_Sync assms(2))
        using *(5) apply (rule disjE)
  
         apply (rule_tac x = ev e # t in exI, rule_tac x = u in exI, 
                rule_tac x = ev e # r in exI, rule_tac x = v in exI)
         apply (simp add: *(1, 2, 3, 4))
         apply (cases u; simp add: notin image_iff T_Mprefix D_Mprefix)
        using *(4) assms(3) apply (fast+)[2]
  
        apply (rule_tac x = t          in exI, rule_tac x = ev e # u in exI,
               rule_tac x = ev e # r in exI, rule_tac x = v          in exI)
         apply (simp add: *(1, 2, 3, 4))
        apply (cases t; simp add: notin image_iff T_Mprefix D_Mprefix)
        using *(4) assms(3) by blast
    qed
  } note * = this

  show s  𝒟 (?rhs A A' P B B' Q)  s  𝒟 (?lhs A A' P B B' Q) for s
    apply (simp add: D_Det)
    apply (erule disjE, rule *, simp_all add: sets_assms(1))
    apply (erule disjE, subst Sync_commute, rule *, simp_all add: sets_assms(3) Sync_commute)
  proof -
    assume s  𝒟 (x  A'  B'  (P x S Q x))
    then obtain e t u r v
      where * : e  A' e  B' s  [] hd s = ev e front_tickFree v tickFree r  v = []
                tl s = r @ v r setinterleaves ((t, u), insert tick (ev ` S))
                t  𝒟 (P e)  u  𝒯 (Q e)  t  𝒟 (Q e)  u  𝒯 (P e) 
      by (simp add: D_Mprefix D_Sync) force
    have inside: e  S using *(1) sets_assms(2) by blast
    show s  𝒟 (?lhs A A' P B B' Q)
      apply (subst list.collapse[OF *(3), symmetric], simp add: D_Sync)
      apply (rule_tac x = ev e # t in exI, rule_tac x = ev e # u in exI,
             rule_tac x = ev e # r in exI, rule_tac x = v in exI)
      by (simp add: * inside D_Mprefix T_Mprefix)
  qed
qed


(* useful version for later *)
lemma Mprefix_Sync_distr_bis: 
  (Mprefix A P) S (Mprefix B Q) =
       (xA - S  (P x S Mprefix B Q)) 
     (yB - S  (Mprefix A P S Q y)) 
     (xA  B  S  (P x S Q x))
  by (subst Mprefix_Sync_distr[of A - S S A  S B - S B  S, simplified Un_Diff_Int])
     (simp_all add: Int_commute inf_left_commute)


lemmas Mprefix_Sync_distr_subset = Mprefix_Sync_distr[where A = {} 
       and B = {}, simplified, simplified Mprefix_STOP Det_STOP trans[OF Det_commute Det_STOP]]
   and Mprefix_Sync_distr_indep = Mprefix_Sync_distr[where A'= {} 
       and B'= {}, simplified, simplified Mprefix_STOP Det_STOP] 
   and Mprefix_Sync_distr_right = Mprefix_Sync_distr[where A = {} 
       and B'= {}, simplified, simplified Mprefix_STOP Det_STOP trans[OF Det_commute Det_STOP], rotated] 
   and Mprefix_Sync_distr_left = Mprefix_Sync_distr[where A'= {} 
       and B = {}, simplified, simplified Mprefix_STOP Det_STOP trans[OF Det_commute Det_STOP]]


lemma Mprefix_Sync_SKIP: "(Mprefix B P  S  SKIP) = ( x   B - S  (P x  S  SKIP))"
proof (auto simp add:Process_eq_spec_optimized, goal_cases)
  case (1 x)
  then show ?case
  proof(simp_all add:D_Sync D_Mprefix D_SKIP T_SKIP, elim exE conjE, goal_cases)
      case (1 t u r v a)
      then show ?case 
        apply(intro conjI) 
          using empty_setinterleaving apply blast
         apply(elim disjE)
          apply (metis (no_types, lifting) DiffI Sync.sym emptyLeftProperty 
                           empty_iff hd_append2 image_diff_subset insertI2 list.exhaust_sel 
                           setinterleaving.simps(2) subsetCE)
          apply (metis D_imp_front_tickFree Sync.sym TickLeftSync empty_iff 
                          empty_setinterleaving event.distinct(1) ftf_Sync21 insertI1 SyncHd_Tl
                          list.expand list.sel(1) list.set_intros(1)  SyncSameHdTl tickFree_def)
          using Sync.sym emptyLeftNonSync emptyLeftProperty hd_in_set apply fastforce
          apply (metis (no_types, lifting) DiffI Sync.sym append_Nil2 event.distinct(1) 
                        image_diff_subset insertI1 insertI2 list.sel(1) subsetCE SyncHd_Tl SyncSameHdTl)
        apply(rule_tac x="a" in exI, intro conjI) 
           apply (metis Sync.sym emptyLeftProperty empty_setinterleaving hd_append2 insertI1 
                       list.sel(1) SyncHd_Tl SyncSameHdTl)
          apply(rule_tac x="tl t" in exI, rule_tac x="u" in exI, 
                rule_tac x="tl r" in exI, rule_tac x="v" in exI)
          by (metis (no_types, lifting) Sync.sym empty_setinterleaving 
                    event.distinct(1) insertI1 list.sel(1) SyncHd_Tl SyncSameHdTl 
                    SyncTlEmpty tickFree_tl tl_append2)
  qed
next
  case (2 x)
  then show ?case 
    proof(simp_all add:D_Sync D_Mprefix D_SKIP T_SKIP, elim exE conjE, goal_cases)
      case (1 a t u r v)
      then show ?case  
        apply(rule_tac x="hd x#t" in exI, rule_tac x="u" in exI, rule_tac x="hd x#r" in exI,
              rule_tac x="v" in exI, auto)      
        using hd_Cons_tl list.exhaust_sel by force+
    qed 
next
  case (3 a b)
  then show ?case
  proof(simp add:F_Sync F_Mprefix F_SKIP, elim exE disjE, simp_all, goal_cases)
    case (1 t u X)
    { fix X Y A B
      assume "b = (X  Y)  insert tick (ev ` B)  X  Y" and "X  ev ` A = {}" and "tick  Y"
      hence "b  ev ` (A - B) = {}" by (rule_tac equals0I, auto) 
    } note l1 = this
    from 1 show ?case
      apply(elim exE conjE disjE)
          using l1 apply simp
         apply(rule disjI2, simp)
        apply(intro disjI2 conjI)
          using empty_setinterleaving apply blast
         apply (metis (no_types, opaque_lifting) DiffI Sync.sym UnI2 contra_subsetD emptyLeftNonSync 
                emptyLeftProperty hd_in_set image_diff_subset insert_is_Un) 
        apply (metis Sync.sym Un_commute emptyLeftProperty list.sel(1) list.sel(3) neq_Nil_conv SyncTlEmpty)
       apply(intro disjI2 conjI)       
         using empty_setinterleaving apply blast
        apply (metis (no_types, opaque_lifting) DiffI Sync.sym event.distinct(1) event.inject 
                     imageE image_eqI insertI1 insertI2 list.sel(1) SyncHd_Tl SyncSameHdTl)
       apply (metis Sync.sym event.distinct(1) insertI1 list.sel(1) SyncHd_Tl SyncSameHdTl)
       done
  next
    case (2 t u r v)
    from 2(2) have "a  𝒟 (Mprefix B P S SKIP)" 
      apply(simp add:D_Sync) using T_SKIP by blast
    with 2(3) have "a  𝒟 ( x   B - S  (P x  S  SKIP))" by simp
    with 2(2) show ?case 
      by (simp add:D_Sync D_Mprefix, rule_tac disjI2, metis)
  qed
next  
  case (4 a b)
  then show ?case
  proof(simp add: F_Sync F_Mprefix F_SKIP, elim exE disjE, simp_all, goal_cases)
    case 1
    then show ?case
      apply(rule_tac disjI1, rule_tac x="[]" in exI, simp, rule_tac x="[]" in exI, simp) 
      apply(rule_tac x="b - (ev ` B)" in exI, rule_tac conjI)
       by (blast, rule_tac x="b - {tick}" in exI, blast) 
  next
    case 2
    then show ?case 
    proof (elim conjE exE, elim disjE exE, simp_all, goal_cases)
      case (1 aa t u X)
      then show ?case      
        apply(erule_tac conjE, erule_tac exE, simp_all)
        apply(rule_tac disjI1, rule_tac x="(ev aa)#t" in exI, rule_tac x=u in exI, 
              rule_tac x=X in exI, intro conjI, simp_all)
        apply auto[1] 
        by (metis (no_types, lifting) DiffE event.distinct(1) event.inject 
            imageE insertE list.exhaust_sel SyncSingleHeadAdd)
    next
      case (2 aa t u r v)
      from 2(2) have "a  𝒟 ( x   B - S  (P x  S  SKIP))" 
        apply(simp add:D_Mprefix D_Sync) by (metis "2"(1) "2"(3) "2"(4))
      with 2(5) have "a  𝒟 (Mprefix B P S SKIP)" by simp
      with 2(2) show ?case by (simp add:D_Sync D_Mprefix)
    qed
  qed
qed

lemma Sync_Ndet_left_distrib: "((P  Q)  S  M) = ((P  S  M)  (Q  S  M))"
  by (auto simp: Process_eq_spec, simp_all add: D_Sync F_Sync D_Ndet F_Ndet T_Ndet) blast+

lemma Sync_Ndet_right_distrib: "(M  S  (P  Q)) = ((M  S  P)  (M  S  Q))"
  by (metis Sync_commute Sync_Ndet_left_distrib)

lemma prefix_Sync_SKIP1:  "a  S  (a  P S SKIP) = (a  (P S SKIP))"
  by (metis (no_types, lifting) write0_def empty_Diff insert_Diff_if Mprefix_Sync_SKIP Mprefix_singl)

lemma prefix_Sync_SKIP2: "a  S  (a  P S SKIP) = STOP"
  by (simp add: Mprefix_STOP Mprefix_Sync_SKIP write0_def)

lemma prefix_Sync_SKIP: "(a  P S SKIP) = (if a  S then STOP else (a  (P S SKIP)))"
  by (auto simp add: prefix_Sync_SKIP2 prefix_Sync_SKIP1)
  
lemma prefix_Sync1: "a  S; b  S; a  b  (a  P S (b  Q)) = STOP"  
  using Mprefix_Sync_distr_subset[of "{a}" S "{b}" "λx. P" "λx. Q", simplified]
  by (auto, simp add: Mprefix_STOP Mprefix_singl)
   
lemma prefix_Sync2: "a  S  ((a  P) S (a  Q)) = (a  (P S Q))"  
  by (simp add:write0_def Mprefix_Sync_distr_subset[of "{a}" S "{a}" "λx. P" "λx. Q", simplified])

lemma prefix_Sync3: "a  S; b  S  (a  P S (b  Q)) = (b  ((a  P) S Q))"
  using Mprefix_Sync_distr_right[of "{b}" S "{a}" "λx. P" "λx. Q", simplified]
  by (auto simp add:write0_def Sync_commute)

lemma Hiding_Sync_D1: finite A  A  S = {}   𝒟 ((P S Q) \ A)  𝒟 ((P \ A) S (Q \ A))
proof (simp only:D_Sync T_Sync D_Hiding T_Hiding, intro subsetI CollectI, 
                  elim CollectE exE conjE, elim exE CollectE disjE, goal_cases)
  case (1 x t u ta ua r v)
  then show ?case (is "t ua ra va. ?P t ua ra va")
    apply (subgoal_tac "?P (trace_hide ta (ev ` A)) (trace_hide ua (ev ` A)) 
                        (trace_hide r (ev ` A)) ((trace_hide v (ev ` A))@u)") 
     apply (metis (no_types, lifting)) 
    apply(simp_all add:front_tickFree_append Hiding_tickFree tickFree_def disjoint_iff_not_equal
                        Hiding_interleave[of "ev ` A" "insert tick (ev ` S)" r ta ua])
      apply(elim conjE, erule_tac disjE, rule_tac disjI1, rule_tac conjI, case_tac "tickFree ta") 
      apply(meson front_tickFree_charn self_append_conv tickFree_def) 
      apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                  insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
    apply(subst disj_commute, rule_tac disjCI, simp)
    subgoal proof(goal_cases)
      case 1
      hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
      from 1(11) 1(10) inf_hidden[of A ua Q] obtain ff where "isInfHiddenRun ff Q A  ua  range ff" by auto
      with 1(2,3,4,7) a show ?case
        apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
        using front_tickFree_Nil tickFree_def by blast
    qed
    apply(rule_tac disjI2, rule_tac conjI, case_tac "tickFree ta") 
      apply(meson front_tickFree_charn self_append_conv tickFree_def) 
      apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                  insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
    apply(subst disj_commute, rule_tac disjCI, simp)
    proof(goal_cases)
      case 1
      hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
      from 1(10) 1(11) inf_hidden[of A ua P] obtain ff where "isInfHiddenRun ff P A  ua  range ff" by auto
      with 1(2,3,4,7) a show ?case
        apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
        using front_tickFree_Nil tickFree_def by blast
    qed
next
  case (2 x t u f)
  then show ?case (is "t ua ra va. ?P t ua ra va")
  proof(elim UnE exE conjE rangeE CollectE, goal_cases 21)
    case (21 xa)
    note aa = 21(7)[rule_format, of xa] 
    with 21 show ?case
    proof(elim UnE exE conjE rangeE CollectE, goal_cases 211 212)
      case (211 taa uaa)
      then show ?case (is "t ua ra va. ?P t ua ra va")
      proof (cases "i. f i  {s. t u. t  𝒯 P  u  𝒯 Q  s setinterleaves ((t, u), ev ` S  {tick})}")
        case True
        define ftu where "ftu  λi. (SOME (t,u). t  𝒯 P  u  𝒯 Q  
                                (f i) setinterleaves ((t, u), ev ` S  {tick}))"
        define ft fu where "ft  fst  ftu" and "fu  snd  ftu"
        have "inj ftu"
        proof
          fix x y
          assume ftuxy: "ftu x = ftu y"
          obtain t u where tu:"(t, u) = ftu x" by (metis surj_pair)
          have "t u. t  𝒯 P  u  𝒯 Q  f x setinterleaves ((t, u), ev ` S  {tick})" 
            using True[rule_format, of x] by simp
          with tu have a:"(f x) setinterleaves ((t, u), ev ` S  {tick})"
            unfolding ftu_def by (metis (mono_tags, lifting) exE_some old.prod.case tu)
          have "t u. t  𝒯 P  u  𝒯 Q  f y setinterleaves ((t, u), ev ` S  {tick})" 
            using True[rule_format, of y] by simp
          with ftuxy tu have b:"(f y) setinterleaves ((t, u), ev ` S  {tick})"
            unfolding ftu_def by (metis (mono_tags, lifting) exE_some old.prod.case tu)
          from interleave_eq_size[OF a b] have "length (f x) = length (f y)" by assumption
          with 211(6) show "x = y"
            by (metis add.left_neutral less_length_mono linorder_neqE_nat not_add_less2 strict_mono_def)
        qed
        hence inf_ftu: "infinite (range ftu)" using finite_imageD by blast
        have "range ftu  range ft × range fu" 
          by (clarify, metis comp_apply fst_conv ft_def fu_def rangeI snd_conv)
        with inf_ftu have inf_ft_fu: "infinite (range ft)  infinite (range fu)" 
          by (meson finite_SigmaI infinite_super)
        have a:"isInfHiddenRun f (P S Q) A"
          using "2"(6) T_Sync by blast
        { fix i
          from a obtain t where "f i = f 0 @ t  set t   (ev ` A)"
            unfolding isInfHiddenRun_1 by blast
          hence "set (f i)  set (f 0)  (ev ` A)" by auto
        } note b = this
        { fix x
          obtain t u where tu:"(t, u) = ftu x" by (metis surj_pair)
          have "t u. t  𝒯 P  u  𝒯 Q  f x setinterleaves ((t, u), ev ` S  {tick})" 
           using True[rule_format, of x] by simp
          with tu have a:"t  𝒯 P  u  𝒯 Q  (f x) setinterleaves ((t, u), ev ` S  {tick})"
           unfolding ftu_def by (metis (mono_tags, lifting) exE_some old.prod.case tu)
          hence "ft x  𝒯 P  fu x  𝒯 Q  (f x) setinterleaves ((ft x, fu x), ev ` S  {tick})"
            by (metis comp_apply fst_conv ft_def fu_def snd_conv tu)
          hence "ft x  𝒯 P  fu x  𝒯 Q  set (ft x)  set (fu x)  set (f x) 
                   (f x) setinterleaves ((ft x, fu x), ev ` S  {tick})" using interleave_set by blast
        } note ft_fu_f = this
        with b have c:"ft i  𝒯 P  fu i  𝒯 Q  set (ft i)  set (fu i)  set (f 0)  ev ` A" for i by blast        
        with inf_ft_fu show ?thesis
        proof(elim disjE, goal_cases 2111 2112)
          case 2111
          have "t'range ft. t = take i t'  (set t  set (f 0)  ev ` A  length t  i)" for i
            by simp (metis "211"(9) b)
          hence "   {t. t'range ft. t = take i t'} 
                  {t. set t  set (f 0)  ev ` A  length t  i} " for i 
            by auto (meson UnE c in_set_takeD subsetCE sup.boundedE)
          with 2(1) finite_lists_length_le[of "set (f 0)  ev ` A"]
            have "finite {t. t'range ft. t = take i t'}" for i
            by (meson List.finite_set finite_Un finite_imageI finite_subset)
          from KoenigLemma[of "range ft", OF 2111(2), rule_format, OF this] 
          obtain ftf::"nat  'a event list" where 
            d:"strict_mono ftf  range ftf  {t. t'range ft. t  t'}" by blast
          with c d[THEN conjunct2] have e:"range ftf  𝒯 P" using is_processT3_ST_pref by blast
          define ftfs where f:"ftfs = ftf  (λn. n + length (f 0))"
          from e d[THEN conjunct1] strict_mono_def have f1:"range ftfs  𝒯 P" and f2:"strict_mono ftfs"
            by (auto simp add: strict_mono_def f)
          { fix i
            have t0:"length (ftfs 0)  length (f 0)" 
              by (metis d[THEN conjunct1] add_leE comp_def f length_strict_mono)
            obtain tt where t1:"ftfs i = (ftfs 0) @ tt" 
              by (metis f2 le0 le_list_def strict_mono_less_eq)
            from d[THEN conjunct2] f obtain j where t2:"ftfs i  ft j" by simp blast
            obtain tt1 where t3: "ft j = (ftfs 0) @ tt @ tt1" 
              by (metis append.assoc le_list_def t1 t2)
            with t0 interleave_order[of "f j" "ftfs 0" "tt@tt1" "ev ` S  {tick}" "fu j"] ft_fu_f 
              have t4:"set tt  set (drop (length (f 0)) (f j))"
                by (metis Un_subset_iff set_append set_drop_subset_set_drop subset_Un_eq)
            with 21 isInfHiddenRun_1[of f _ A] have t5: "set (drop (length (f 0)) (f j))  ev ` A"
              by (metis (full_types) a append_eq_conv_conj) 
            with t4 have "set tt  ev ` A" by simp
            with t1 have "trace_hide (ftfs i) (ev ` A) = trace_hide (ftfs 0) (ev ` A)"
              by (simp add: subset_eq)
          } note f3 = this
          from d[THEN conjunct2] f obtain i where f4:"ftfs 0  ft i" by simp blast
          show ?case 
            apply(rule_tac x="trace_hide (ft i) (ev ` A)" in exI, 
                  rule_tac x="trace_hide (fu i) (ev ` A)" in exI)
            apply(rule_tac x="trace_hide (f i) (ev ` A)" in exI, rule_tac x="u" in exI)
          proof (intro conjI, goal_cases 21111 21112 21113 21114 21115)
            case 21111
            then show ?case using 2 by (simp add: "211"(3))
          next
            case 21112
            then show ?case by (metis "211"(4) "211"(9) a Hiding_tickFree) 
          next
            case 21113
            then show ?case by (metis "211"(5) "211"(8) "211"(9)) 
          next
            case 21114
            then show ?case 
              apply(rule Hiding_interleave)
               using "211"(2) apply blast 
              using ft_fu_f by simp
          next
            case 21115
            from f4 obtain u where f5:"ft i = (ftfs 0) @ u" by (metis le_list_def)
            have "tickFree (f i)" by (metis "211"(4) "211"(8) "211"(9) Hiding_tickFree)
            with ft_fu_f have f6:"tickFree (ft i)" by (meson subsetCE sup.boundedE tickFree_def)
            show ?case
              apply (rule disjI1, rule conjI, simp)
               apply(rule_tac x="ftfs 0" in exI, rule_tac x="trace_hide u (ev ` A)" in exI, intro conjI)
                  apply (metis f5 front_tickFree_Nil front_tickFree_mono ft_fu_f
                               Hiding_fronttickFree is_processT2_TR)
              apply (metis f5 f6 tickFree_append)
                apply (simp add: f5, rule disjI2, rule_tac x=ftfs in exI)  
               using f1 f2 f3 apply blast
              using elemTIselemHT[of "fu i" Q A, simplified T_Hiding] ft_fu_f by blast
          qed 
        next
          case 2112
          have "t'range fu. t = take i t'  (set t  set (f 0)  ev ` A  length t  i)" for i
            by simp (metis "211"(9) b)
          hence "   {t. t'range fu. t = take i t'} 
                   {t. set t  set (f 0)  ev ` A  length t  i} " for i 
            by auto (meson UnE c in_set_takeD subsetCE sup.boundedE)
          with 2(1) finite_lists_length_le[of "set (f 0)  ev ` A"] 
          have "finite {t. t'range fu. t = take i t'}" for i
            by (meson List.finite_set finite_Un finite_imageI finite_subset)
          from KoenigLemma[of "range fu", OF 2112(2), rule_format, OF this] 
          obtain fuf::"nat  'a event list" where 
            d:"strict_mono fuf  range fuf  {t. t'range fu. t  t'}" by blast
          with c d[THEN conjunct2] have e:"range fuf  𝒯 Q" using is_processT3_ST_pref by blast
          define fufs where f:"fufs = fuf  (λn. n + length (f 0))"
          from e d[THEN conjunct1] strict_mono_def have f1:"range fufs  𝒯 Q" and f2:"strict_mono fufs"
            by (auto simp add: strict_mono_def f)
          { fix i
            have t0:"length (fufs 0)  length (f 0)" 
              by (metis d[THEN conjunct1] add_leE comp_def f length_strict_mono)
            obtain tt where t1:"fufs i = (fufs 0) @ tt" 
              by (metis f2 le0 le_list_def strict_mono_less_eq)
            from d[THEN conjunct2] f obtain j where t2:"fufs i  fu j" by simp blast
            obtain tt1 where t3: "fu j = (fufs 0) @ tt @ tt1" by (metis append.assoc le_list_def t1 t2)
            with t0 interleave_order[of "f j" "fufs 0" "tt@tt1" "ev ` S  {tick}" "ft j"] ft_fu_f 
              have t4:"set tt  set (drop (length (f 0)) (f j))"
                by (metis (no_types, opaque_lifting) Sync.sym Un_subset_iff order_trans 
                                                set_append set_drop_subset_set_drop)
            with 21 isInfHiddenRun_1[of f _ A] have t5: "set (drop (length (f 0)) (f j))  ev ` A"
              by (metis (full_types) a append_eq_conv_conj) 
            with t4 have "set tt  ev ` A" by simp
            with t1 have "trace_hide (fufs i) (ev ` A) = trace_hide (fufs 0) (ev ` A)"
              by (simp add: subset_eq)
          } note f3 = this
          from d[THEN conjunct2] f obtain i where f4:"fufs 0  fu i" by simp blast
          show ?case 
            apply(rule_tac x="trace_hide (fu i) (ev ` A)" in exI, 
                  rule_tac x="trace_hide (ft i) (ev ` A)" in exI)
            apply(rule_tac x="trace_hide (f i) (ev ` A)" in exI, rule_tac x="u" in exI)
          proof (intro conjI, goal_cases 21111 21112 21113 21114 21115)
            case 21111
            then show ?case using 2 by (simp add: "211"(3))
          next
            case 21112
            then show ?case by (metis "211"(4) "211"(9) a Hiding_tickFree) 
          next
            case 21113
            then show ?case by (metis "211"(5) "211"(8) "211"(9)) 
          next
            case 21114
            then show ?case 
              apply(rule Hiding_interleave)
               using "211"(2) apply blast 
              using ft_fu_f using Sync.sym by blast
          next
            case 21115
            from f4 obtain u where f5:"fu i = (fufs 0) @ u" by (metis le_list_def)
            have "tickFree (f i)" by (metis "211"(4) "211"(8) "211"(9) Hiding_tickFree)
            with ft_fu_f have f6:"tickFree (fu i)" by (meson subsetCE sup.boundedE tickFree_def)
            show ?case
              apply (rule disjI2, rule conjI, simp)
               apply(rule_tac x="fufs 0" in exI, rule_tac x="trace_hide u (ev ` A)" in exI, intro conjI)
                  apply (metis f5 front_tickFree_Nil front_tickFree_mono ft_fu_f 
                                  Hiding_fronttickFree is_processT2_TR)
              apply (metis f5 f6 tickFree_append)
                apply (simp add: f5, rule disjI2, rule_tac x=fufs in exI)  
               using f1 f2 f3 apply blast
              using elemTIselemHT[of "ft i" P A, simplified T_Hiding] ft_fu_f by blast             
          qed 
        qed
      next
        case False
        then obtain xaa 
          where "f xaa  {s. t u. t  𝒯 P  u  𝒯 Q  s setinterleaves ((t, u), ev ` S  {tick})}" 
            by blast
        with 211(7)[rule_format, of xaa] obtain ta ua ra va 
          where bb:"front_tickFree va  (tickFree ra  va = [])  
                    f xaa = ra @ va  ra setinterleaves ((ta, ua), ev ` S  {tick})  
                    (ta  𝒟 P  ua  𝒯 Q  ta  𝒟 Q  ua  𝒯 P)" by blast
        from 211 have cc:"x = trace_hide (f xaa) (ev ` A) @ u" by (metis (no_types, lifting))
        from bb 211(9) "211"(8) "21"(4) have "tickFree ra  tickFree va" 
          by (metis Hiding_tickFree tickFree_append)
        with cc bb 211 show ?thesis
          apply(subgoal_tac "?P (trace_hide ta (ev ` A)) (trace_hide ua (ev ` A)) 
                             (trace_hide ra (ev ` A))  ((trace_hide va (ev ` A))@u)")
           apply (metis (no_types, lifting))
          apply(simp_all add:front_tickFree_append Hiding_tickFree tickFree_def disjoint_iff_not_equal 
                                      Hiding_interleave[of "ev ` A" "insert tick (ev ` S)" ra ta ua])
            apply(elim conjE disjE, rule_tac disjI1, rule_tac conjI, case_tac "tickFree ta") 
              apply(meson front_tickFree_charn self_append_conv tickFree_def) 
              apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                          insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
         apply(subst disj_commute, rule_tac disjCI, simp)
          subgoal proof(goal_cases 2111)
          case 2111
          hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
          from 2111(20) 2111(21) inf_hidden[of A ua Q] obtain ff 
            where "isInfHiddenRun ff Q A  ua  range ff" by auto
          with 2111(2,3,4,7) a show ?case
            apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
            using front_tickFree_Nil tickFree_def by blast
          qed
          apply(rule_tac disjI2, rule_tac conjI, case_tac "tickFree ta") 
            apply(meson front_tickFree_charn self_append_conv tickFree_def) 
            apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                        insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
          apply(subst disj_commute, rule_tac disjCI, simp)
          proof(goal_cases 2111)
            case 2111
            hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
            from 2111(20) 2111(21) inf_hidden[of A ua P] obtain ff 
              where "isInfHiddenRun ff P A  ua  range ff" by auto
            with 2111(2,3,4,7) a show ?case
              apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
              using front_tickFree_Nil tickFree_def by blast
          qed
      qed      
    next
      case (212 ta ua r v)
      then show ?case (is "t ua ra va. ?P t ua ra va")
        apply (subgoal_tac "?P (trace_hide ta (ev ` A)) (trace_hide ua (ev ` A)) 
                               (trace_hide r (ev ` A)) ((trace_hide v (ev ` A))@u)") 
       apply (metis (no_types, lifting))
      apply(simp_all add:front_tickFree_append Hiding_tickFree tickFree_def disjoint_iff_not_equal
                         Hiding_interleave[of "ev ` A" "insert tick (ev ` S)" r ta ua])
      apply(erule_tac disjE, rule_tac disjI1, rule_tac conjI, case_tac "tickFree ta") 
        apply(meson front_tickFree_charn self_append_conv tickFree_def) 
        apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                    insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
      apply(subst disj_commute, rule_tac disjCI, simp)
      subgoal proof(goal_cases 2121)
        case 2121
        hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
        from 2121(14) 2121(13) inf_hidden[of A ua Q] obtain ff 
          where "isInfHiddenRun ff Q A  ua  range ff" by auto
        with 2121(2,3,4,7) a show ?case
          apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
          using front_tickFree_Nil tickFree_def by blast
      qed
      apply(rule_tac disjI2, rule_tac conjI, case_tac "tickFree ta") 
        apply(meson front_tickFree_charn self_append_conv tickFree_def) 
        apply (metis D_imp_front_tickFree emptyLeftNonSync ftf_Sync21 ftf_Sync32 in_set_conv_decomp_last 
                    insertI1 is_processT2_TR nonTickFree_n_frontTickFree tickFree_Nil tickFree_def)
      apply(subst disj_commute, rule_tac disjCI, simp)
      proof(goal_cases 2121)
        case 2121
        hence a:"tickFree ua" by (metis front_tickFree_implies_tickFree is_processT2_TR is_processT5_S7)
        from 2121(14) 2121(13) inf_hidden[of A ua P] obtain ff 
          where "isInfHiddenRun ff P A  ua  range ff" by auto
        with 2121(2,3,4,7) a show ?case
          apply(rule_tac x=ua in exI, rule_tac x="[]" in exI)
          using front_tickFree_Nil tickFree_def by blast
      qed
    qed
  qed
qed

lemma Hiding_Sync_D2: 
  assumes *:"A  S = {}"
  shows     𝒟 ((P \ A) S (Q \ A))  𝒟 ((P S Q) \ A)
proof -
  { fix P Q   
    have {s. t u r v. front_tickFree v  (tickFree r  v = []) 
           s = r @ v  r setinterleaves ((t, u), insert tick (ev ` S)) 
           (t  𝒟 (P \ A)  u  𝒯 (Q \ A))}  𝒟 ((P S Q) \ A)
    proof(simp add:D_Hiding D_Sync, intro subsetI CollectI, elim exE conjE CollectE, goal_cases a)
      case (a x t u r v ta1 ta2)
      from a(1,3-9) show ?case
      proof(erule_tac disjE, goal_cases)
        case 1
        with interleave_append[of r "trace_hide ta1 (ev ` A)" "ta2" "insert tick (ev ` S)" u] 
        obtain u1 u2 r1 r2
          where a1:"u = u1 @ u2" and a2:"r = r1 @ r2" and 
                a3:"r1 setinterleaves ((trace_hide ta1 (ev ` A), u1), insert tick (ev ` S))" and
                a4:"r2 setinterleaves ((ta2, u2), insert tick (ev ` S))" by blast
        with 1 show ?case
        proof(auto simp only:T_Hiding, goal_cases 11 12 13)
          case (11 ua) 
          from trace_hide_append[OF 11(12)] 
          obtain ua1 where a5:"u1 = trace_hide ua1 (ev ` A)  ua1  ua  ua1  𝒯 Q" 
            using "11"(13) F_T is_processT3_ST_pref le_list_def by blast
          from interleave_Hiding[OF _ 11(10)[simplified a5]] obtain ra1
            where a6:"r1 = trace_hide ra1 (ev ` A)  ra1 setinterleaves ((ta1, ua1), insert tick (ev ` S))"
            using * by blast
          from a(2) 11 a5 a6 show ?case
            apply(exI ra1, exI "r2@v", intro conjI, simp_all (asm_lr))
              apply (metis a(5) append_Nil2 front_tickFree_append 
                           front_tickFree_mono ftf_Sync is_processT2_TR)
             apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
            using front_tickFree_Nil by blast
        next
          case (12 ua1 ua2)          
          then show ?case 
          proof(cases "u1  trace_hide ua1 (ev ` A)")
            case True
            then obtain uu1 where  "u1@uu1 = trace_hide ua1 (ev ` A)" using le_list_def by blast
            with trace_hide_append[OF this] obtain uaa1 
              where a5:"u1 = trace_hide uaa1 (ev ` A)  uaa1  ua1  uaa1  𝒯 Q"
              using "12"(15) NT_ND is_processT3_ST_pref le_list_def by blast
            from interleave_Hiding[OF _ 12(10)[simplified a5]] obtain rr1
              where a6:"r1 = trace_hide rr1 (ev ` A)  
                        rr1 setinterleaves ((ta1, uaa1), insert tick (ev ` S))"
              using * by blast
            from a(2) 12 a5 a6 show ?thesis
            apply(exI rr1, exI "r2@v", intro conjI, simp_all (asm_lr))
              apply (metis a(5) append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR)
             apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
            using front_tickFree_Nil by blast
          next
            case False
            with 12(14) obtain uaa1 where "u1 = trace_hide ua1 (ev ` A)@uaa1"
              by (metis append_eq_append_conv2 le_list_def)
            with a3 interleave_append_sym[of r1 "trace_hide ta1 (ev ` A)" "insert tick (ev ` S)"  
                 "trace_hide ua1 (ev ` A)" uaa1]  
            obtain taa1 taa2 ra1 ra2
              where aa1:"trace_hide ta1 (ev ` A) = taa1 @ taa2" and aa2:"r1 = ra1 @ ra2" and 
                aa3:"ra1 setinterleaves ((taa1, trace_hide ua1 (ev ` A)), insert tick (ev ` S))" and
                aa4:"ra2 setinterleaves ((taa2,uaa1), insert tick (ev ` S))" by blast
            with trace_hide_append[OF aa1[symmetric]] 
            obtain taaa1 where a5:"taa1 = trace_hide taaa1 (ev ` A)  taaa1  ta1  taaa1  𝒯 P"
              using "12"(7) D_T is_processT3_ST_pref le_list_def by blast
            with interleave_Hiding[OF _ aa3[simplified a5]] obtain rr1
              where a6:"ra1 = trace_hide rr1 (ev ` A)  rr1 setinterleaves ((taaa1, ua1), insert tick (ev ` S))"
              using * by blast
            from a(2) 12 a5 show ?thesis
              apply(exI rr1, exI "ra2@r2@v", intro conjI, simp_all (asm_lr))
                 apply (metis aa2 front_tickFree_append front_tickFree_mono ftf_Sync 
                              Hiding_tickFree self_append_conv tickFree_append)          
                apply (metis a6 ftf_Sync1 le_list_def tickFree_append tickFree_def)
               using a6 aa2 apply blast 
              using Sync.sym a6 front_tickFree_Nil by blast
          qed
        next
          case (13 ua fa xa)
          with isInfHiddenRun_1[of fa Q] have a0:"i. t. fa i = fa 0 @ t  set t   (ev ` A)" by simp
          define tlf where "tlf  λi. drop (length (fa 0)) (fa i)"
          have tlf_def2:"(fa x) = (fa 0) @ (tlf x)" for x by (metis a0 append_eq_conv_conj tlf_def)
          { fix x y
            assume *:"(x::nat) < y"
            hence "fa x = fa 0 @ tlf x  fa y = fa 0 @ tlf y" by (metis tlf_def2)
            hence  "tlf x < tlf y"
              using strict_monoD[OF 13(16), of x y] by (simp add: A "*" le_list_def)
          } note tlf_strict_mono = this
          have tlf_range:"set (tlf i)    (ev ` A)" for i 
            by (metis a0 append_eq_conv_conj tlf_def)
          from 13 show ?case 
          proof(cases "u1  trace_hide (fa xa) (ev ` A)")
            case True
            then obtain uu1 where  "u1@uu1 = trace_hide (fa xa) (ev ` A)" using le_list_def by blast
            with trace_hide_append[OF this] 
            obtain uaa1 where a5:"u1 = trace_hide uaa1 (ev ` A)  uaa1  (fa xa)  uaa1  𝒯 Q"
              by (metis "13"(17) is_processT3_ST le_list_def)
            from interleave_Hiding[OF _ 13(10)[simplified a5]] obtain rr1
              where a6:"  r1 = trace_hide rr1 (ev ` A) 
                         rr1 setinterleaves ((ta1, uaa1), insert tick (ev ` S))"
              using * by blast
            from a(2) 13 a5 a6 show ?thesis
            apply(exI rr1, exI "r2@v", intro conjI, simp_all (asm_lr))
              apply (metis a(5) append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR)
             apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
            using front_tickFree_Nil by blast
          next
            case False
            with 13(14) obtain uaa1 where "u1 = trace_hide (fa 0) (ev ` A)@uaa1"
              by (metis "13"(18) append_eq_append_conv2 le_list_def)
            with a3 interleave_append_sym[of r1 "trace_hide ta1 (ev ` A)" "insert tick (ev ` S)"  
                 "trace_hide (fa 0) (ev ` A)" uaa1]  
            obtain taa1 taa2 ra1 ra2
              where aa1:"trace_hide ta1 (ev ` A) = taa1 @ taa2" and aa2:"r1 = ra1 @ ra2" and 
                aa3:"ra1 setinterleaves ((taa1, trace_hide (fa 0) (ev ` A)), insert tick (ev ` S))" and
                aa4:"ra2 setinterleaves ((taa2,uaa1), insert tick (ev ` S))" by blast
            with trace_hide_append[OF aa1[symmetric]] 
            obtain taaa1 where a5:"taa1 = trace_hide taaa1 (ev ` A)  taaa1  ta1  taaa1  𝒯 P"
              using "13"(7) D_T is_processT3_ST_pref le_list_def by blast
            with interleave_Hiding[OF _ aa3[simplified a5]] obtain rr1
              where a6:"ra1 = trace_hide rr1 (ev ` A)  
                        rr1 setinterleaves ((taaa1, (fa 0)), insert tick (ev ` S))"
              using * by blast
            from a(2) 13 a0 a5 a6 aa1 aa2 aa3 show ?thesis
              apply(exI rr1, exI "ra2@r2@v", intro conjI, simp_all (asm_lr))
                apply (metis front_tickFree_append front_tickFree_mono ftf_Sync 
                             Hiding_tickFree self_append_conv tickFree_append)          
                apply (metis a6 ftf_Sync1 le_list_def tickFree_append tickFree_def)
             proof (rule_tac disjI2, exI "λi. rr1@(tlf i)", intro conjI, goal_cases 131 132 133 134)
               case 131
               then show ?case 
                 apply(rule_tac strict_monoI, drule_tac tlf_strict_mono,rule_tac less_append) by assumption
             next
               case 132
               have "(rr1@tlf i) setinterleaves ((taaa1, fa i),insert tick (ev ` S))" for i
                 apply(subst tlf_def2, rule interleave_append_tail_sym[OF a6[THEN conjunct2], of "tlf i"])
                 using * tlf_range by blast
               then show ?case
                 unfolding T_Sync using a5 13(17) by auto
             next
               case 133
               from tlf_range have "trace_hide (y @ tlf i) (ev ` A) = trace_hide y (ev ` A)" for i y 
                 apply(induct y) using filter_empty_conv apply fastforce by simp
               then show ?case by simp
             next
               case 134
               have "tlf 0 = []"
                 by (simp add: tlf_def)
               then show ?case by simp
             qed  
          qed  
        qed
      next
        case 2
        from 2(8) obtain nta::nat and ff::"nat  'a event list" 
          where "strict_mono ff" and ff:"(i. ff i  𝒯 P)  ta1 = ff nta  
                (i. trace_hide (ff i) (ev ` A) = trace_hide (ff 0) (ev ` A))" by blast
        define f where "f  (λi. ff (i + nta))"
        with ff have f1:"strict_mono f" and f2:"(i. f i  𝒯 P)" and f3:"ta1 = f 0" and 
                f4:"(i. trace_hide (f i) (ev ` A) = trace_hide ta1 (ev ` A))"
          apply auto apply(rule strict_monoI, rule strict_mono ff[THEN strict_monoD])
          by simp metis
        with isInfHiddenRun_1[of f P] have a0:"i. t. f i = f 0 @ t  set t   (ev ` A)" by simp
        define tlf where "tlf  λi. drop (length (f 0)) (f i)"
        have tlf_def2:"(f x) = ta1 @ (tlf x)" for x by (metis a0 f3 append_eq_conv_conj tlf_def)
        { fix x y
          assume *:"(x::nat) < y"
          hence "f x = f 0 @ tlf x  f y = f 0 @ tlf y" by (metis f3 tlf_def2)
          hence  "tlf x < tlf y"
            using strict_monoD[OF f1, of x y] by (simp add: A "*" le_list_def)
        } note tlf_strict_mono = this
        have tlf_range:"set (tlf i)    (ev ` A)" for i 
          by (metis a0 append_eq_conv_conj tlf_def)
        with 2 interleave_append[of r "trace_hide ta1 (ev ` A)" "ta2" "insert tick (ev ` S)" u] 
        obtain u1 u2 r1 r2
          where a1:"u = u1 @ u2" and a2:"r = r1 @ r2" and 
                a3:"r1 setinterleaves ((trace_hide ta1 (ev ` A), u1), insert tick (ev ` S))" and
                a4:"r2 setinterleaves ((ta2, u2), insert tick (ev ` S))" by blast
        with 2(1-6) f1 f2 f3 f4 show ?case
        proof(auto simp only:T_Hiding, goal_cases 21 22 23)
          case (21 ua) 
          from trace_hide_append[OF 21(14)] obtain ua1 
            where a5:"u1 = trace_hide ua1 (ev ` A)  ua1  ua  ua1  𝒯 Q" 
            using "21"(15) F_T is_processT3_ST_pref le_list_def by blast
          from interleave_Hiding[OF _ a3[simplified a5]] obtain ra1
            where a6:"r1 = trace_hide ra1 (ev ` A)  ra1 setinterleaves ((ta1, ua1), insert tick (ev ` S))"
            using * by blast
          from a(2) 21 a5 a6 show ?case 
            apply(exI ra1, exI "r2@v", intro conjI, simp_all (asm_lr))
              apply (metis a(5) append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR)
             apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def) 
             proof (rule_tac disjI2, exI "λi. ra1@(tlf i)", intro conjI, goal_cases 211 212 213 214)
               case 211
               then show ?case 
                 by(rule_tac strict_monoI, drule_tac tlf_strict_mono, rule_tac less_append)(assumption)
             next
               case 212
               have "(ra1@tlf i) setinterleaves ((f i, ua1),insert tick (ev ` S))" for i
                 apply(subst tlf_def2, rule interleave_append_tail[OF a6[THEN conjunct2], of "tlf i"])
                 using * tlf_range by blast
               then show ?case
                 unfolding T_Sync using a5 21(15) f2 by auto
             next
               case 213
               from tlf_range have "trace_hide (y @ tlf i) (ev ` A) = trace_hide y (ev ` A)" for i y 
                 apply(induct y) using filter_empty_conv apply fastforce by simp
               then show ?case by simp
             next
               case 214
               have "tlf 0 = []"
                 by (simp add: tlf_def)
               then show ?case by simp
             qed              
        next
          case (22 ua1 ua2)
          then show ?case
          proof(cases "u1  trace_hide ua1 (ev ` A)")
            case True
            then obtain uu1 where  "u1@uu1 = trace_hide ua1 (ev ` A)" using le_list_def by blast
            from trace_hide_append[OF this] 
            obtain uaa1 where a5:"u1 = trace_hide uaa1 (ev ` A)  uaa1  ua1  uaa1  𝒯 Q" 
              using "22"(17) D_T is_processT3_ST le_list_def by blast
            from interleave_Hiding[OF _ a3[simplified a5]] 
            obtain ra1
              where a6:"  r1 = trace_hide ra1 (ev ` A) 
                         ra1 setinterleaves ((ta1, uaa1), insert tick (ev ` S))"
              using * by blast
            from a(2) 22 a5 a6 show ?thesis
              apply(exI ra1, exI "r2@v", intro conjI, simp_all (asm_lr))
                apply (metis a(5) append_Nil2 front_tickFree_append 
                                  front_tickFree_mono ftf_Sync is_processT2_TR)
               apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
             proof (rule_tac disjI2, exI "λi. ra1@(tlf i)", intro conjI, goal_cases 211 212 213 214)
               case 211
               then show ?case apply(rule_tac strict_monoI, drule_tac tlf_strict_mono, rule_tac less_append) by assumption
             next
               case 212
               have "(ra1@tlf i) setinterleaves ((f i, uaa1),insert tick (ev ` S))" for i
                 apply(subst tlf_def2, rule interleave_append_tail[OF a6[THEN conjunct2], of "tlf i"])
                 using * tlf_range by blast
               then show ?case
                 unfolding T_Sync using a5 22(15) f2 by auto
             next
               case 213
               from tlf_range have "trace_hide (y @ tlf i) (ev ` A) = trace_hide y (ev ` A)" for i y 
                 apply(induct y) using filter_empty_conv apply fastforce by simp
               then show ?case by simp
             next
               case 214
               have "tlf 0 = []"
                 by (simp add: tlf_def)
               then show ?case by simp
             qed  
          next
            case False
            with 22(16) obtain uaa1 where "u1 = trace_hide ua1 (ev ` A)@uaa1"
              by (metis append_eq_append_conv2 le_list_def)
            with a3 interleave_append_sym[of r1 "trace_hide ta1 (ev ` A)" "insert tick (ev ` S)"  "
                 trace_hide ua1 (ev ` A)" uaa1]  
            obtain taa1 taa2 ra1 ra2
              where aa1:"trace_hide ta1 (ev ` A) = taa1 @ taa2" and aa2:"r1 = ra1 @ ra2" and 
                aa3:"ra1 setinterleaves ((taa1, trace_hide ua1 (ev ` A)), insert tick (ev ` S))" and
                aa4:"ra2 setinterleaves ((taa2,uaa1), insert tick (ev ` S))" by blast
            with trace_hide_append[OF aa1[symmetric]] 
            obtain taaa1 where a5:"taa1 = trace_hide taaa1 (ev ` A)  taaa1  ta1  taaa1  𝒯 P"
              using f2 f3 is_processT3_ST_pref le_list_def by metis
            with interleave_Hiding[OF _ aa3[simplified a5]] obtain rr1
              where a6:"ra1 = trace_hide rr1 (ev ` A)  
                        rr1 setinterleaves ((taaa1, ua1), insert tick (ev ` S))"
              using * by blast
            from a(2) 22 a5 show ?thesis
              apply(exI rr1, exI "ra2@r2@v", intro conjI, simp_all (asm_lr))
                 apply (metis a(5) a(8) aa2 front_tickFree_append front_tickFree_mono is_processT2_TR
                              ftf_Sync Hiding_tickFree   self_append_conv tickFree_append)                
                apply (metis a6 ftf_Sync1 le_list_def tickFree_append tickFree_def)
               using a6 aa2 apply blast 
              using Sync.sym a6[THEN conjunct2] front_tickFree_Nil by (metis append_Nil2)
          qed
        next
          case (23 ua fa xa)
          with isInfHiddenRun_1[of fa Q] have a0:"i. t. fa i = fa 0 @ t  set t   (ev ` A)" by simp
          define tlfa where "tlfa  λi. drop (length (fa 0)) (fa i)"
          have tlfa_def2:"(fa x) = (fa 0) @ (tlfa x)" for x by (metis a0 append_eq_conv_conj tlfa_def)
          { fix x y
            assume *:"(x::nat) < y"
            hence "fa x = fa 0 @ tlfa x  fa y = fa 0 @ tlfa y" by (metis tlfa_def2)
            hence  "tlfa x < tlfa y"
              using strict_monoD[OF 23(18), of x y] by (simp add: A "*" le_list_def)
          } note tlfa_strict_mono = this
          have tlfa_range:"set (tlfa i)    (ev ` A)" for i 
            by (metis a0 append_eq_conv_conj tlfa_def)
          from 23 show ?case 
          proof(cases "u1  trace_hide (fa xa) (ev ` A)")
            case True
            then obtain uu1 where  "u1@uu1 = trace_hide (fa xa) (ev ` A)" using le_list_def by blast
            with trace_hide_append[OF this] 
            obtain uaa1 where a5:"u1 = trace_hide uaa1 (ev ` A)  uaa1  (fa xa)  uaa1  𝒯 Q"
              by (metis "23"(19) is_processT3_ST le_list_def)
            from interleave_Hiding[OF _ a3[simplified a5]] 
            obtain rr1
              where a6:"r1 = trace_hide rr1 (ev ` A)  rr1 setinterleaves ((ta1, uaa1), insert tick (ev ` S))"
              using * by blast
            from a(2) 23 a5 a6 show ?thesis
            apply(exI rr1, exI "r2@v", intro conjI, simp_all (asm_lr))
            apply (metis a(5) append_Nil2 front_tickFree_append front_tickFree_mono 
                                  ftf_Sync is_processT2_TR)
            apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
            proof (rule_tac disjI2, exI "λi. rr1@(tlf i)", intro conjI, goal_cases 211 212 213 214)
               case 211
               then show ?case 
                 apply(rule_tac strict_monoI, drule_tac tlf_strict_mono, rule_tac less_append) by assumption
             next
               case 212
               have "(rr1@tlf i) setinterleaves ((f i, uaa1),insert tick (ev ` S))" for i
                 apply(subst tlf_def2, rule interleave_append_tail[OF a6[THEN conjunct2], of "tlf i"])
                 using * tlf_range by blast
               then show ?case
                 unfolding T_Sync using a5 23(17) f2 by auto
             next
               case 213
               from tlf_range have "trace_hide (y @ tlf i) (ev ` A) = trace_hide y (ev ` A)" for i y 
                 apply(induct y) using filter_empty_conv apply fastforce by simp
               then show ?case by simp
             next
               case 214
               have "tlf 0 = []"
                 by (simp add: tlf_def)
               then show ?case by simp
             qed  
          next
            case False
            with 23(16) obtain uaa1 where "u1 = trace_hide (fa 0) (ev ` A)@uaa1"
              by (metis "23"(20) append_eq_append_conv2 le_list_def)
            with a3 interleave_append_sym[of r1 "trace_hide ta1 (ev ` A)" 
                                                "insert tick (ev ` S)"  
                                                "trace_hide (fa 0) (ev ` A)" uaa1]  
            obtain taa1 taa2 ra1 ra2
              where aa1:"trace_hide ta1 (ev ` A) = taa1 @ taa2" and aa2:"r1 = ra1 @ ra2" and 
                aa3:"ra1 setinterleaves ((taa1, trace_hide (fa 0) (ev ` A)), insert tick (ev ` S))" and
                aa4:"ra2 setinterleaves ((taa2,uaa1), insert tick (ev ` S))" by blast
            with trace_hide_append[OF aa1[symmetric]] 
            obtain taaa1 where a5:"taa1 = trace_hide taaa1 (ev ` A)  taaa1  ta1  taaa1  𝒯 P"
              by (metis f2 f3 is_processT3_ST le_list_def)
            with interleave_Hiding[OF _ aa3[simplified a5]] obtain rr1
              where a6:"ra1 = trace_hide rr1 (ev ` A)  
                        rr1 setinterleaves ((taaa1, (fa 0)), insert tick (ev ` S))"
              using * by blast
            from a(2) 23 a0 a5 a6 aa1 aa2 aa3 show ?thesis
              apply(exI rr1, exI "ra2@r2@v", intro conjI, simp_all (asm_lr))
                apply (metis a(5) a(8) front_tickFree_append front_tickFree_mono ftf_Sync 
                                       Hiding_tickFree is_processT2_TR self_append_conv)
                apply (metis a6 ftf_Sync1 le_list_def tickFree_append tickFree_def)
             proof (rule_tac disjI2, exI "λi. rr1@(tlfa i)", intro conjI, goal_cases 131 132 133 134)
               case 131
               then show ?case 
                 by(rule_tac strict_monoI, drule_tac tlfa_strict_mono, rule_tac less_append) assumption
             next
               case 132
               have "(rr1@tlfa i) setinterleaves ((taaa1, fa i),insert tick (ev ` S))" for i
                 apply(subst tlfa_def2, rule interleave_append_tail_sym[OF a6[THEN conjunct2], of "tlfa i"])
                 using * tlfa_range by blast
               then show ?case
                 unfolding T_Sync using a5 23(19) by auto
             next
               case 133
               from tlfa_range have "trace_hide (y @ tlfa i) (ev ` A) = trace_hide y (ev ` A)" for i y 
                 apply(induct y) using filter_empty_conv apply fastforce by simp
               then show ?case by simp
             next
               case 134
               have "tlfa 0 = []"
                 by (simp add: tlfa_def)
               then show ?case by simp
             qed  
          qed  
        qed
      qed
    qed
  }
  from this[of P Q] this[of Q P] Sync_commute[of P S Q] show ?thesis
    by (simp add:D_Sync T_Sync) blast
qed

lemma Hiding_Sync: 
  finite A  A  S = {}  ((P S Q) \ A) = ((P \ A) S (Q \ A))
proof(auto simp add: Process_eq_spec_optimized subset_antisym[OF Hiding_Sync_D1 Hiding_Sync_D2], 
      simp_all add: F_Sync F_Hiding,
      goal_cases)
  case (1 a b)
  then show ?case 
  proof(elim disjE, goal_cases 11 12)
    case 11
    then show ?case
    proof(elim exE conjE, elim disjE, goal_cases 111 112)
      case (111 c)
      from 111(7) obtain t u X Y where
        a: "(t, X)   P" and
        b: "(u, Y)   Q" and 
        c: "c setinterleaves ((t, u), insert tick (ev ` S))" and
        d: "b   ev ` A = (X  Y)  insert tick (ev ` S)  X  Y" by auto
      from 1(2) d have e:"ev ` A  X  Y" by blast 
      from a b c d e 111(2,3) show ?case
        apply(rule_tac disjI1)
        apply(rule_tac x="trace_hide t (ev ` A)" in exI, rule_tac x="trace_hide u (ev ` A)" in exI)
        apply(rule_tac x="X - ((ev ` A) - b)" in exI, intro conjI disjI1, rule_tac x="t" in exI)
         apply (metis Int_subset_iff Un_Diff_Int Un_least is_processT4 sup_ge1)
        apply(rule_tac x="Y - ((ev ` A) - b)" in exI, intro conjI disjI1, rule_tac x="u" in exI)
         apply (metis Int_subset_iff Un_Diff_Int Un_least is_processT4 sup_ge1)
        using Hiding_interleave[of "ev ` A" "insert tick (ev ` S)" c t u] by blast+
    next
      case (112 t)
      from 112(7) have a:"front_tickFree t" 
        by (metis (mono_tags, opaque_lifting) D_imp_front_tickFree append_Nil2 
                  front_tickFree_append ftf_Sync is_processT2_TR)
      from 112 have "t  𝒟 (P S Q)" by (simp add:D_Sync)
      with 112(1,2,3) have a  𝒟 ((P S Q) \ A)
        apply (simp add:D_Hiding)
        proof(case_tac "tickFree t", goal_cases 1121 1122)
          case 1121
          then show ?case 
            by (rule_tac x=t in exI, rule_tac x="[]" in exI, simp)
        next
          case 1122
          with a obtain t' where "t = t'@[tick]" using nonTickFree_n_frontTickFree by blast
          with a show ?case 
            apply (rule_tac x="t'" in exI, rule_tac x="[tick]" in exI, auto)
             using front_tickFree_mono apply blast
            using 1122(4) is_processT9 by blast
        qed
      then show ?case
        apply(rule_tac disjI2)
        using Hiding_Sync_D1[of A S P Q, OF 112(1,2)] D_Sync[of P \ A S Q \ A] by auto
    qed
  next
    case 12
    hence a  𝒟 ((P S Q) \ A) by (simp add:D_Hiding)
    then show ?case
      apply(rule_tac disjI2)
      using Hiding_Sync_D1[of A S P Q, OF 12(1,2)] D_Sync[of P \ A S Q \ A] by auto
  qed 
next
  case (2 a b)
  then show ?case
  proof(elim disjE, goal_cases 21 22)
    case 21
    then show ?case
    proof(elim exE conjE, elim disjE, goal_cases 211 212 213 214)
      case (211 t u X Y)
      then obtain ta ua where t211: "t = trace_hide ta (ev ` A)  (ta, X  ev ` A)   P" and 
                              u211: "u = trace_hide ua (ev ` A)  (ua, Y  ev ` A)   Q" by blast
      from interleave_Hiding[of "(ev ` A)" "insert tick (ev ` S)" a ta ua] "211"(1,2,3) t211 u211 
      obtain aa  where a211: "a = trace_hide aa  (ev ` A)  
                              aa setinterleaves ((ta, ua), insert tick (ev ` S))" by blast
      with 211(1,2,3,4) t211 u211 show ?case
        apply(rule_tac disjI1, rule_tac x="aa" in exI, simp)
        apply(rule_tac disjI1, rule_tac x="ta" in exI, rule_tac x="ua" in exI)
        apply(rule_tac x="X  ev ` A" in exI, rule conjI) using is_processT4 apply blast
        apply(rule_tac x="Y  ev ` A" in exI, rule conjI) using is_processT4 by blast+
    next
      case (212 t u X Y)
      hence u  𝒟 (Q \ A) and t  𝒯 (P \ A)  
         apply (simp add:D_Hiding)
        using "212"(8) F_T elemTIselemHT by blast
      with 212(3,8) have a  𝒟 (((P \ A) S (Q \ A))) 
        apply (simp add:D_Sync)
        using Sync.sym front_tickFree_charn by blast
      then show ?case
        apply (rule_tac disjI2)
        using Hiding_Sync_D2[of A S P Q, OF 2(2)] D_Hiding[of "(P S Q)", simplified] by auto
    next
      case (213 t u X Y)
      hence u  𝒯 (Q \ A) and t  𝒟 (P \ A)  
        by (simp_all add:D_Hiding, metis F_T elemTIselemHT)
      with 213(3,8) have a  𝒟 (((P \ A) S (Q \ A)))
        apply (simp add:D_Sync)
        using Sync.sym front_tickFree_charn by blast
      then show ?case
        apply (rule_tac disjI2)
        using Hiding_Sync_D2[of A S P Q, OF 2(2)] D_Hiding[of "(P S Q)", simplified] by auto
    next
      case (214 t u X Y)
      hence u  𝒯 (Q \ A) and t  𝒟 (P \ A)
        by (simp_all add:D_Hiding T_Hiding)
      with 214(3,8) have a  𝒟 (((P \ A) S (Q \ A)))
        apply (simp add:D_Sync)
        using Sync.sym front_tickFree_charn by blast
      then show ?case
        apply (rule_tac disjI2)
        using Hiding_Sync_D2[of A S P Q, OF 2(2)] D_Hiding[of "(P S Q)", simplified] by auto
    qed
  next
    case 22
    hence a  𝒟 (((P \ A) S (Q \ A))) by (simp add:D_Sync)
    then show ?case
      apply (rule_tac disjI2)
      using Hiding_Sync_D2[of A S P Q, OF 2(2)] D_Hiding[of "(P S Q)", simplified] by auto
  qed 
qed

lemma Sync_assoc_oneside_D: "𝒟 (P S (Q S T))  𝒟 (P S Q S T)"
proof(auto simp add:D_Sync T_Sync del:disjE, goal_cases a)
  case (a tt uu rr vv)
  from a(3,4) show ?case
  proof(auto, goal_cases)
    case (1 t u)
    with interleave_assoc_2[OF 1(5) 1(1)] obtain tu 
      where *:"tu setinterleaves ((tt, t), insert tick (ev ` S))" 
        and **:"rr setinterleaves ((tu, u), insert tick (ev ` S))"
      by blast
    with a(1,2) 1 show ?case by (metis append.right_neutral front_tickFree_charn) 
  next
    case (2 t u u1 u2)
    with interleave_append_sym [OF 2(1)] obtain t1 t2 r1 r2
      where a1:"tt = t1 @ t2" and a2:"rr = r1 @ r2" 
        and a3:"r1 setinterleaves ((t1, u1), insert tick (ev ` S))" 
        and a4:"r2 setinterleaves ((t2, u2), insert tick (ev ` S))" by blast
    with interleave_assoc_2[OF 2(5) a3] obtain tu 
      where *:"tu setinterleaves ((t1, t), insert tick (ev ` S))" 
       and **:"r1 setinterleaves ((tu, u), insert tick (ev ` S))"
      by blast
    with a1 a2 a3 a(1,2) 2 show ?case 
      apply(exI tu, exI u, exI r1, exI "r2@vv", intro conjI, simp_all) 
        apply (metis D_imp_front_tickFree append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync)
       using D_imp_front_tickFree front_tickFree_append front_tickFree_mono ftf_Sync apply blast
      by (metis NT_ND Sync.sym append_Nil2 front_tickFree_Nil is_processT3_ST)
  next
    case (3 v u u1 u2)
    with interleave_append_sym [OF 3(1)] obtain t1 t2 r1 r2
      where a1:"tt = t1 @ t2" and a2:"rr = r1 @ r2" 
       and  a3:"r1 setinterleaves ((t1, u1), insert tick (ev ` S))" 
       and  a4:"r2 setinterleaves ((t2, u2), insert tick (ev ` S))" by blast
    with interleave_assoc_2[OF _ a3, of u v] obtain tu 
      where *:"tu setinterleaves ((t1, u), insert tick (ev ` S))" 
       and **:"r1 setinterleaves ((tu, v), insert tick (ev ` S))"
      using Sync.sym 3(5) by blast
    with a1 a2 a3 a(1,2) 3 show ?case 
      apply(exI v, exI tu, exI r1, exI "r2@vv", intro conjI, simp_all) 
        apply (metis D_imp_front_tickFree append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync)
      using D_imp_front_tickFree front_tickFree_append front_tickFree_mono ftf_Sync apply blast
      using Sync.sym apply blast by (meson D_T is_processT3_ST)
  next
    case (4 t u)
    with interleave_assoc_2[OF 4(3) 4(1)] obtain tu 
      where *:"tu setinterleaves ((tt, t), insert tick (ev ` S))" 
       and **:"rr setinterleaves ((tu, u), insert tick (ev ` S))"
      by blast
    with a(1,2) 4 show ?case 
      apply(exI tu, exI u, exI rr, exI vv, simp) using NT_ND front_tickFree_Nil by blast
  next
    case (5 t u)
    with interleave_assoc_2[OF _ 5(1), of u t] obtain tu 
      where *:"tu setinterleaves ((tt, u), insert tick (ev ` S))" 
       and **:"rr setinterleaves ((tu, t), insert tick (ev ` S))"
      using Sync.sym by blast
    with a(1,2) 5 show ?case 
      apply(exI tu, exI t, exI rr, exI vv, simp) using NT_ND front_tickFree_Nil by blast
  next
    case (6 t u u1 u2)
    with interleave_append [OF 6(1)] obtain t1 t2 r1 r2
      where a1:"uu = t1 @ t2" and a2:"rr = r1 @ r2" 
        and a3:"r1 setinterleaves ((t1, u1), insert tick (ev ` S))" 
        and a4:"r2 setinterleaves ((t2, u2), insert tick (ev ` S))" using Sync.sym by blast
    with interleave_assoc_2[OF 6(5) a3] obtain tu 
      where *:"tu setinterleaves ((t1, t), insert tick (ev ` S))" 
       and **:"r1 setinterleaves ((tu, u), insert tick (ev ` S))"
      by blast
    with a1 a2 a3 a(1,2) 6 show ?case 
      apply(exI tu, exI u, exI r1, exI "r2@vv", intro conjI, simp_all) 
        apply (metis append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR) 
       apply (meson front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR) 
      by (metis Sync.sym append_Nil2 front_tickFree_Nil is_processT3_ST)
  next
    case (7 v u t1 t2)
    with interleave_append [OF 7(1)] obtain u1 u2 r1 r2
      where a1:"uu = u1 @ u2" and a2:"rr = r1 @ r2" 
       and  a3:"r1 setinterleaves ((t1, u1), insert tick (ev ` S))" 
       and  a4:"r2 setinterleaves ((t2, u2), insert tick (ev ` S))" by blast
    with interleave_assoc_2[of t1 u _ v r1 u1] obtain tu 
      where *:"tu setinterleaves ((u1, u), insert tick (ev ` S))" 
       and **:"r1 setinterleaves ((tu, v), insert tick (ev ` S))"
      using 7(5) Sync.sym by blast
    with a1 a2 a3 a(1,2) 7 show ?case 
      apply(exI v, exI tu, exI r1, exI "r2@vv", intro conjI, simp_all) 
        apply (metis append_Nil2 front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR) 
       apply (meson front_tickFree_append front_tickFree_mono ftf_Sync is_processT2_TR) 
      using Sync.sym apply blast by (meson D_T is_processT3_ST)
  next
    case (8 t u)
    with interleave_assoc_2[OF 8(3), of rr uu] obtain tu 
      where *:"tu setinterleaves ((uu, t), insert tick (ev ` S))" 
       and **:"rr setinterleaves ((tu, u), insert tick (ev ` S))"
      using Sync.sym by blast
    with a(1,2) 8 show ?case 
      apply(exI tu, exI u, exI rr, exI vv, simp) using Sync.sym front_tickFree_Nil by blast
  next
    case (9 t u)
    with interleave_assoc_1[OF 9(3), of rr uu] obtain uv 
      where *:"uv setinterleaves ((u, uu), insert tick (ev ` S))" 
       and **:"rr setinterleaves ((t, uv), insert tick (ev ` S))"
      by blast
    with a(1,2) 9 show ?case 
      apply(exI t, exI uv, exI rr, exI vv, simp) using Sync.sym front_tickFree_Nil by blast
  qed
qed

lemma Sync_assoc_oneside: "((P S Q) S T)  (P S (Q S T))"
proof(unfold le_ref_def, rule conjI, goal_cases D F)
  case D
  then show ?case using Sync_assoc_oneside_D by assumption
next
  case F
  then show ?case
  unfolding F_Sync proof(rule Un_least, goal_cases FF DD)
    case (FF)
    then show ?case
    proof(rule subsetI, simp add:D_Sync T_Sync split_paired_all, elim exE conjE disjE, goal_cases)
      case (1 r Xtuv t uv Xt Xuv u v Xu Xv)
      with interleave_assoc_2[OF 1(6), OF 1(2)] obtain tu
        where *:"tu setinterleaves ((t, u), insert tick (ev ` S))" 
        and **:"r setinterleaves ((tu, v), insert tick (ev ` S))" by blast
      with 1(1,3,4,5,7) show ?case 
        apply(rule_tac disjI1, exI tu, exI v, exI "(Xt  Xu)  insert tick (ev ` S)  Xt  Xu", 
              intro conjI disjI1, simp_all) 
        by blast+
    next
      case (2 r Xtuv t uv Xt Xuv u v uv1 uv2)
      with interleave_append_sym [of r t _ uv1 uv2] obtain t1 t2 r1 r2
        where a1:"t = t1 @ t2" and a2:"r = r1 @ r2" 
          and a3:"r1 setinterleaves ((t1, uv1), insert tick (ev ` S))" 
          and a4:"r2 setinterleaves ((t2, uv2), insert tick (ev ` S))" by metis
      with interleave_assoc_2[OF 2(6), OF a3] obtain tu
        where *:"tu setinterleaves ((t1, u), insert tick (ev ` S))" 
         and **:"r1 setinterleaves ((tu, v), insert tick (ev ` S))" by blast
      from 2(1) a1 obtain Xt1 where ***:"(t1, Xt1)   P" using is_processT3_SR by blast
      from 2 a1 a2 a3 a4 * ** *** show ?case
        apply(rule_tac disjI2, exI tu, exI v, exI r1, exI r2, intro conjI disjI1, simp_all) 
          apply (metis front_tickFree_charn front_tickFree_mono ftf_Sync is_processT2) 
         apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
        using F_T Sync.sym front_tickFree_Nil by blast
    next
      case (3 r Xtuv t uv Xt Xuv v u uv1 uv2)
      with interleave_append_sym [of r t _ uv1 uv2] obtain t1 t2 r1 r2
        where a1:"t = t1 @ t2" and a2:"r = r1 @ r2" 
         and  a3:"r1 setinterleaves ((t1, uv1), insert tick (ev ` S))" 
         and  a4:"r2 setinterleaves ((t2, uv2), insert tick (ev ` S))" by metis
      with interleave_assoc_2[OF _ a3, of u v] obtain tu
        where *:"tu setinterleaves ((t1, u), insert tick (ev ` S))" 
         and **:"r1 setinterleaves ((tu, v), insert tick (ev ` S))" using "3"(6) Sync.sym by blast
      from 3(1) a1 obtain Xt1 
        where ***:"(t1, Xt1)   P" using is_processT3_SR by blast
      from 3 a1 a2 a3 a4 * ** *** show ?case
        apply(rule_tac disjI2, exI v, exI tu, exI r1, exI r2, intro conjI, simp_all) 
          apply (metis front_tickFree_charn front_tickFree_mono ftf_Sync is_processT2) 
         apply (metis equals0D ftf_Sync1 ftf_Sync21 insertI1 tickFree_def)
        using Sync.sym F_T by blast+ 
    next
      case (4 r Xtuv t uv Xt Xuv u v uv1 uv2)
      with interleave_assoc_2[OF 4(6), of r t] obtain tu
        where *:"tu setinterleaves ((t, u), insert tick (ev ` S))" 
         and **:"r setinterleaves ((tu, v), insert tick (ev ` S))" by auto
      from 4 * **  show ?case
        apply(rule_tac disjI2, exI tu, exI v, exI r, exI "[]", intro conjI, simp_all) 
        by (metis "4"(4) F_T Sync.sym append.right_neutral)
    next
      case (5 r Xtuv t uv Xt Xuv v u uv1 uv2)
      from 5(2,7,5,6)  interleave_assoc_2[of uv u _ v r t] obtain tu
        where *:"tu setinterleaves ((t, u), insert tick (ev ` S))" 
         and **:"r setinterleaves ((tu, v), insert tick (ev ` S))" by (metis Sync.sym append_Nil2)
      from 5 * **  show ?case
        apply(rule_tac disjI2, exI v, exI tu, exI r, exI "[]", intro conjI, simp_all)
        using Sync.sym F_T by blast+
    qed
  next
    case (DD)
    then show ?case
      using Sync_assoc_oneside_D[of P S Q T] by (simp add:D_Sync Collect_mono_iff sup.coboundedI2) 
  qed
qed

lemma Sync_assoc: "((P S Q) S T) = (P S (Q S T))"
  by (metis antisym_conv Sync_assoc_oneside Sync_commute)

subsection‹ Derivative Operators laws  ›

(* Trivial results have been removed *)
lemmas Par_BOT = Sync_BOT[where S = UNIV]
   and Par_SKIP_SKIP = Sync_SKIP_SKIP[where S = UNIV]
   and Par_SKIP_STOP = Sync_SKIP_STOP[where S = UNIV]
   and Par_commute = Sync_commute[where S = UNIV]
   and Par_assoc = Sync_assoc[where S = UNIV]
   and Par_Ndet_right_distrib = Sync_Ndet_right_distrib[where S = UNIV]
   and Par_Ndet_left_distrib = Sync_Ndet_left_distrib[where S = UNIV]
   and Mprefix_Par_SKIP = Mprefix_Sync_SKIP[where S = UNIV]
   and prefix_Par_SKIP = prefix_Sync_SKIP[where S = UNIV, simplified]
   and mono_Par_FD = mono_Sync_FD[where S = UNIV]
   and mono_Par_ref = mono_Sync_ref[where S = UNIV]
   and prefix_Par1 = prefix_Sync1[where S = UNIV, simplified]
   and prefix_Par2 = prefix_Sync2[where S = UNIV, simplified]
   and Mprefix_Par_distr = Mprefix_Sync_distr_subset[where S = UNIV, simplified]

   and Inter_BOT = Sync_BOT[where S = {}]
   and Inter_SKIP_SKIP = Sync_SKIP_SKIP[where S = {}]
   and Inter_SKIP_STOP = Sync_SKIP_STOP[where S = {}]
   and Inter_commute = Sync_commute[where S = {}]
   and Inter_assoc = Sync_assoc[where S = {}]
   and Inter_Ndet_right_distrib = Sync_Ndet_right_distrib[where S = {}]
   and Inter_Ndet_left_distrib = Sync_Ndet_left_distrib[where S = {}]
   and Mprefix_Inter_SKIP = Mprefix_Sync_SKIP[where S = {}, simplified, simplified Mprefix_STOP]
   and prefix_Inter_SKIP = prefix_Sync_SKIP[where S = {}, simplified]
   and mono_Inter_FD = mono_Sync_FD[where S = {}]
   and mono_Inter_ref = mono_Sync_ref[where S = {}]
   and Hiding_Inter = Hiding_Sync[where S = {}, simplified]
   and Mprefix_Inter_distr = Mprefix_Sync_distr_indep[where S = {}, simplified]
   and prefix_Inter = Mprefix_Sync_distr_indep[of {a} {} {b} λx. P λx. Q,
                                               simplified, folded write0_def] for a P b Q



lemma Inter_SKIP: "(P ||| SKIP) = P"  
proof(auto simp:Process_eq_spec D_Sync F_Sync F_SKIP D_SKIP T_SKIP, goal_cases)
  case (1 a t X Y)
  then have aa:"(X  Y)  {tick}  X  Y  X" by (simp add: Int_Un_distrib2)
  have "front_tickFree t" using "1"(1) is_processT2 by blast
  with 1 EmptyLeftSync[of a "{tick}" t] have bb:"a=t"
    using Sync.sym by blast
  from 1(1) aa bb show ?case using is_processT4 by blast
next
  case (2 a t X Y)
  have "front_tickFree t" using 2(1) is_processT2 by blast
  with 2 TickLeftSync[of "{tick}" t a] have bb:"a=t  last t=tick"
    using Sync.sym by blast
  with 2 have "a  𝒯 P  last a = tick" using F_T by blast
  with tick_T_F[of "butlast a" P "(X  Y)  {tick}  X  Y"] show ?case 
    by (metis "2"(2) EmptyLeftSync bb self_append_conv2 snoc_eq_iff_butlast)
next
  case (3 b t r v)
  with 3 EmptyLeftSync[of r "{tick}" t] have bb:"r=t"
    using Sync.sym by blast
  with 3 show ?case using is_processT by blast
next
  case (4 b t r v)
  with TickLeftSync[of "{tick}" t r, simplified] have bb:"r=t"
    using D_imp_front_tickFree Sync.sym by blast
  with 4 show ?case using is_processT by blast
next
  case (5 b t r)
  with EmptyLeftSync[of r "{tick}" t] have bb:"r=t"
    using Sync.sym by blast
  with 5 show ?case using is_processT by blast
next
  case (6 b t r)
  with TickLeftSync[of "{tick}" t r, simplified] have bb:"r=t"
    using D_imp_front_tickFree Sync.sym by blast
  with 6 show ?case using is_processT by blast
next
  case (7 a b)
  then show ?case 
    apply(cases "tickFree a")
     apply(rule_tac x=a in exI, rule_tac x="[]" in exI, rule_tac x=b in exI, simp)
     apply(rule_tac x="b - {tick}" in exI, simp, intro conjI)
      using emptyLeftSelf[of a "{tick}"] Sync.sym tickFree_def apply fastforce
     apply blast
    apply(rule_tac x=a in exI, rule_tac x="[tick]" in exI, rule_tac x=b in exI, simp, rule conjI)
    subgoal proof -
      assume a1: "¬ tickFree a"
      assume a2: "(a, b)   P"
      then obtain ees :: "'a event list  'a event list" where
        f3: "a = ees a @ [tick]"
        using a1 by (meson is_processT2 nonTickFree_n_frontTickFree)
      then have "ees a setinterleaves (([], ees a), {tick})"
        using a2 by (metis (no_types) DiffD2 Diff_insert_absorb emptyLeftSelf 
                                      front_tickFree_implies_tickFree is_processT2 tickFree_def)
      then show "a setinterleaves ((a, [tick]), {tick})"
        using f3 by (metis (no_types) Sync.sym addSyncEmpty insertI1)
    qed
    apply(rule_tac x="b - {tick}" in exI) by blast
next
  case (8 t r v)
  with EmptyLeftSync[of r "{tick}" t] have bb:"r=t"
    using Sync.sym by blast
  with 8 show ?case using is_processT by blast
next
  case (9 t r v)
  with TickLeftSync[of "{tick}" t r, simplified] have bb:"r=t"
    using D_imp_front_tickFree Sync.sym by blast
  with 9 show ?case using is_processT by blast
next
  case (10 t r)
  with EmptyLeftSync[of r "{tick}" t] have bb:"r=t"
    using Sync.sym by blast
  with 10 show ?case by simp
next
  case (11 t r)
  with TickLeftSync[of "{tick}" t r, simplified] have bb:"r=t"
    using D_imp_front_tickFree Sync.sym by blast
  with 11 show ?case by simp
next
  case (12 x)
  then show ?case 
  proof(cases "tickFree x")
    case True
    with 12 show ?thesis 
      apply(rule_tac x=x in exI, rule_tac x="[]" in exI, 
            rule_tac x=x in exI, rule_tac x="[]" in exI, simp)
      by (metis Sync.sym emptyLeftSelf singletonD tickFree_def)
  next
    case False
    with 12 show ?thesis 
      apply(rule_tac x="butlast x" in exI, rule_tac x="[]" in exI, 
            rule_tac x="butlast x" in exI, rule_tac x="[tick]" in exI, simp, intro conjI)
         apply (metis D_imp_front_tickFree append_butlast_last_id front_tickFree_mono 
                      list.distinct(1) tickFree_Nil)  
      using NT_ND T_nonTickFree_imp_decomp apply fastforce 
       apply (metis NT_ND Sync.sym append_T_imp_tickFree append_butlast_last_id emptyLeftSelf 
                    list.distinct(1) singletonD tickFree_Nil tickFree_def)
      using D_imp_front_tickFree is_processT9 nonTickFree_n_frontTickFree by fastforce
  qed
qed

lemma Inter_STOP_Seq_STOP: "(P ||| STOP) = (P  ;  STOP)"
proof (auto simp add:Process_eq_spec D_Sync F_Sync F_STOP D_STOP T_STOP F_Seq D_Seq, goal_cases)
  case (1 a t X Y)
  have "insert tick ((X  Y)  {tick}  X  Y)  X  {tick}" by blast
  with 1 show ?case
    by (metis (mono_tags, lifting) EmptyLeftSync Sync.sym is_processT 
                                   is_processT5_S2 no_Trace_implies_no_Failure)
next
  case (2 a t X)
  then show ?case using EmptyLeftSync Sync.sym tickFree_def by fastforce
next
  case (3 b t r v)
  then show ?case using EmptyLeftSync Sync.sym is_processT7 by blast
next
  case (4 t r v)
  then show ?case using EmptyLeftSync Sync.sym is_processT7 by blast
next
  case (5 b t r)
  then show ?case using EmptyLeftSync Sync.sym is_processT7 by blast
next
  case (6 t r)
  then show ?case using EmptyLeftSync Sync.sym is_processT7 by blast
next
  case (7 a b)
  then show ?case 
    apply(rule_tac x=a in exI, rule_tac x="b" in exI, intro conjI)
      apply (meson insert_iff is_processT subsetI)
     using emptyLeftSelf[of a "{tick}"] Sync.sym tickFree_def apply fastforce   
    by blast
next
  case (8 a b)
  then show ?case 
    apply(rule_tac x=a in exI, rule_tac x="b-{tick}" in exI, intro conjI)
      apply (meson NF_NT is_processT6)
     using emptyLeftSelf[of a "{tick}"] Sync.sym tickFree_def 
     apply (metis append_T_imp_tickFree list.distinct(1) singletonD)
    by blast
next
  case (9 t X)
  then show ?case
    apply (cases tickFree t)
    by (metis Sync.sym append.right_neutral emptyLeftSelf front_tickFree_Nil singletonD tickFree_def)
       (metis D_T D_imp_front_tickFree Sync.sym append_single_T_imp_tickFree emptyLeftSelf 
        front_tickFree_single is_processT9_S_swap nonTickFree_n_frontTickFree singletonD tickFree_def)
next
  case (10 t r v)
  then show ?case using EmptyLeftSync Sync.sym is_processT7 by blast
next
  case (11 t r)
  then show ?case using Sync.sym emptyLeftProperty by blast
next
  case (12 t)
  then show ?case
    apply (cases tickFree t)
     apply (rule_tac x = t in exI, rule_tac x = t in exI, simp,
            metis Sync.sym emptyLeftSelf singletonD tickFree_def)
    by (rule_tac x = butlast t in exI, rule_tac x = butlast t in exI, 
        rule_tac x = [tick] in exI, simp,
        metis D_imp_front_tickFree Sync.sym emptyLeftSelf front_tickFree_implies_tickFree tickFree_def
              is_processT9_S_swap nonTickFree_n_frontTickFree singletonD snoc_eq_iff_butlast)
qed


lemma Par_STOP: "P    (P || STOP) = STOP"  
proof(auto simp add:Process_eq_spec, 
      simp_all add:D_Sync F_Sync F_STOP D_STOP T_STOP is_processT2 D_imp_front_tickFree F_UU D_UU,
      goal_cases)
  case (1 a b aa ba)
  then show ?case
  proof(elim exE conjE disjE, goal_cases)
    case (1 t X Y)
    then show ?case
      proof(cases t)
        case Nil then show ?thesis using "1"(4) EmptyLeftSync by blast
      next
        case (Cons a list)
        with 1 show ?thesis by (simp split:if_splits, cases a, simp_all)
      qed 
  next
    case (2 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 2 show ?thesis by simp
    next
      case (Cons a list)
      with 2 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 2(1,2) show ?case using NF_ND is_processT7 by fastforce 
  next
    case (3 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 3 show ?thesis by simp
    next
      case (Cons a list)
      with 3 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 3(1,2) show ?case using NF_ND is_processT7 by fastforce 
  qed
next
  case (2 a b aa ba)
  then show ?case
    apply(rule_tac disjI1, rule_tac x="[]" in exI, rule_tac x="{}" in exI, simp, rule_tac conjI)
    using is_processT apply blast
    apply(rule_tac x=ba in exI, rule_tac set_eqI, rule_tac iffI)
    using event_set apply blast
    by fast
next
  case (3 a b x)
  then show ?case 
  proof(elim exE conjE disjE, goal_cases)
    case (1 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 1 show ?thesis by simp
    next
      case (Cons a list)
      with 1 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 3(1,2) show ?case using NF_ND is_processT7 by fastforce
  next
    case (2 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 2 show ?thesis by simp
    next
      case (Cons a list)
      with 2 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 3(1,2) show ?case using NF_ND is_processT7 by fastforce
  qed
next
  case (4 x a b)
  then show ?case
  proof(elim exE conjE disjE, goal_cases)
    case (1 t X Y)
    then show ?case
      proof(cases t)
        case Nil then show ?thesis using "1"(4) EmptyLeftSync by blast
      next
        case (Cons a list)
        with 1 show ?thesis by (simp split:if_splits, cases a, simp_all)
      qed 
  next
    case (2 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 2 show ?thesis by simp
    next
      case (Cons a list)
      with 2 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 2(1,2) show ?case using NF_ND is_processT7 by fastforce 
  next
    case (3 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 3 show ?thesis by simp
    next
      case (Cons a list)
      with 3 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
  with 3(1,2) show ?case using NF_ND is_processT7 by fastforce 
  qed 
next
  case (5 x a b)
  then show ?case
  apply(rule_tac disjI1, rule_tac x="[]" in exI, rule_tac x="{}" in exI, simp, rule_tac conjI)
  using is_processT apply blast
  apply(rule_tac x=b in exI, rule_tac set_eqI, rule_tac iffI)
  using event_set apply blast
  by fast
next
  case (6 x xa)
  then show ?case
  proof(elim exE conjE disjE, goal_cases)
    case (1 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 1 show ?thesis by simp
    next
      case (Cons a list)
      with 1 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 6(1,2) show ?case using NF_ND is_processT7 by fastforce
  next
    case (2 t r v)
    hence "[]  𝒟 P"
    proof(cases t)
      case Nil with 2 show ?thesis by simp
    next
      case (Cons a list)
      with 2 show ?thesis by (simp split:if_splits, cases a, simp_all)
    qed 
    with 6(1,2) show ?case using NF_ND is_processT7 by fastforce
  qed
qed


  
section‹Multiple Non Deterministic Operator Laws›

lemma Mprefix_refines_Mndetprefix: "( x  A  P x)  ( x  A  P x)"
proof(cases "A = {}")
  case True
  then show ?thesis by (simp add: Mprefix_STOP)
next
  case False
  then show ?thesis 
    by (auto simp add:le_ref_def D_Mprefix write0_def F_Mprefix F_Mndetprefix D_Mndetprefix)
qed

lemma Mndetprefix_refine_FD: "a  A  ( x  A  (P x))  (a  (P a))"
  by(subgoal_tac "A  {}", auto simp:le_ref_def D_Mndetprefix F_Mndetprefix)

lemma Mndetprefix_subset_FD:"A  {}  (xa A  B   P)  (xa A   P)"
  by (simp add: D_Mndetprefix F_Mndetprefix le_ref_def)

lemma mono_Mndetprefix_FD[simp]: "x  A. P x  P' x  ( x  A  (P x))  ( x  A  (P' x))"
  apply(cases "A  {}", auto simp:le_ref_def D_Mndetprefix F_Mndetprefix)
  by(meson contra_subsetD le_ref_def mono_write0_FD)+ 

lemma Mndetprefix_FD_subset : "A  {}  A  B  (( x  B  P x)   ( x  A  P x))"
  by (metis bot.extremum_uniqueI Mndetprefix_Un_distrib mono_Ndet_FD_right order_refl sup.absorb_iff1)

section ‹ Infra-structure for Communication Primitives ›

lemma read_read_Sync:
  assumes contained: "(y. c y  S)"
    shows "((c?x  P x) S (c?x  Q x)) = (c?x  ((P x) S (Q x)))"
proof -
  have A: "range c  S" by (insert contained, auto)
  show ?thesis by (auto simp: read_def o_def Set.Int_absorb2 Mprefix_Sync_distr_subset A)
qed

lemma read_read_non_Sync:
  "y. c y  S; y. d y  S  (c?x  (P x)) S (d?x (Q x)) = c?x  ((P x) S (d?x (Q x)))"
  apply (auto simp add: read_def o_def)
  using Mprefix_Sync_distr_right[of "range c" S "range d" "λx. Q (inv d x)" "λx. P (inv c x)"]
  apply (subst (1 2) Sync_commute)
  by auto

lemma write_read_Sync:
  assumes contained: "y. c y  S"
      and is_construct: "inj c"
    shows "(c!a  P) S (c?x  Q x) = (c!a  (P S Q a))"
proof -
  have A : "range c  S" by (insert contained, auto)
  have B : " {c a}  range c  S = {c a}" by (insert contained, auto)
  show ?thesis
    apply (simp add: read_def write_def o_def, subst Mprefix_Sync_distr_subset)
    by (simp_all add: A B contained Mprefix_singl is_construct)
qed

lemma write_read_non_Sync:
  "d a  S; y. c y  S   (d!a  P) S (c?x  Q x) = d!a  (P S (c?x  Q x))"
  apply (simp add: read_def o_def write_def)
  using Mprefix_Sync_distr_right[of "{d a}" S "range c" "λx. (Q (inv c x))" "λx. P"]
  apply (subst (1 2) Sync_commute)
  by auto
 
lemma write0_read_non_Sync:
  "d  S; y. c y  S  (d  P) S (c?x  Q x) = c?x  ((d  P) S Q x)"
  apply (simp add: read_def o_def)
  apply (subst (1 2)  Mprefix_singl[symmetric])
  apply (subst Mprefix_Sync_distr_right)
  by auto
  
lemma write0_write_non_Sync:
 "d a  C; c  C  (c  Q) C (d!a  P) = d!a  ((c  Q) C P)"
  apply(simp add: write_def )
  apply(subst (1 2) Mprefix_singl[symmetric])
  by (auto simp: Mprefix_Sync_distr_right)




section ‹Renaming operator laws›

lemma Renaming_BOT: Renaming  f = 
  by (fastforce simp add: F_UU D_UU F_Renaming D_Renaming EvExt_tF EvExt_ftF
                          Process_eq_spec front_tickFree_append intro: tickFree_Nil)+
  

lemma Renaming_STOP: Renaming STOP f = STOP
  by (subst Process_eq_spec) (simp add: EvExt_ftF F_STOP D_STOP F_Renaming D_Renaming)


lemma Renaming_SKIP: Renaming SKIP f = SKIP
  by (subst Process_eq_spec) (force simp add: EvExt_def F_SKIP D_SKIP F_Renaming D_Renaming)



lemma Renaming_Ndet: Renaming (P  Q) f = Renaming P f  Renaming Q f
  by (subst Process_eq_spec) (auto simp add: F_Renaming D_Renaming F_Ndet D_Ndet)


lemma Renaming_Det:  Renaming (P  Q) f = Renaming P f  Renaming Q f
proof (subst Process_eq_spec, intro iffI conjI subset_antisym)
  show  (Renaming (P  Q) f)   (Renaming P f  Renaming Q f)
    apply (simp add: F_Renaming D_Renaming T_Renaming F_Det D_Det, safe,
           simp_all add: is_processT6_S2)
    by blast+ (metis EvExt_eq_tick, meson map_EvExt_tick)+
next 
  show  (Renaming P f  Renaming Q f)   (Renaming (P  Q) f)
    apply (simp add: F_Renaming D_Renaming T_Renaming F_Det D_Det, safe, simp_all)
    by blast+ (metis EvExt_eq_tick, metis Cons_eq_append_conv EvExt_tF 
                     list.map_disc_iff tickFree_Cons)+
next
  show 𝒟 (Renaming (P  Q) f)  𝒟 (Renaming P f  Renaming Q f)
    by (auto simp add: D_Renaming D_Det)
next
  show 𝒟 (Renaming P f  Renaming Q f)  𝒟 (Renaming (P  Q) f)
    by (auto simp add: D_Renaming D_Det)
qed




(* lemma THE_inj_trivial: ‹inj f ⟹ (THE x. f x = f a) = a› by (simp add: inj_eq)

lemma THE_inj_on_trivial: ‹inj_on f A ⟹ a ∈ A ⟹ (THE x. x  ∈ A ∧ f x = f a) = a› 
  by (simp add: inj_onD the_equality)
 *)

(* TODO: Move this in Mprefix and Mndetprefix theories *)

lemma mono_Mprefix_eq: a  A. P a = Q a  Mprefix A P = Mprefix A Q
  by (subst Process_eq_spec, auto simp add: F_Mprefix D_Mprefix)

lemma mono_Mndetprefix_eq: a  A. P a = Q a  Mndetprefix A P = Mndetprefix A Q
  by (cases A = {}, simp) (subst Process_eq_spec, auto simp add: F_Mndetprefix D_Mndetprefix)




lemma Renaming_Mprefix: Renaming ( a  A  P (f a)) f =  b  f ` A  Renaming (P b) f
proof (subst Process_eq_spec, intro conjI subset_antisym)
  show  (Renaming ( a  A  P (f a)) f)   ( b  f ` A  Renaming (P b) f)
    apply (simp add: F_Renaming F_Mprefix D_Mprefix, safe; 
           auto simp add: hd_map_EvExt map_tl tickFree_tl)
    by ((meson disjoint_iff ev_elem_anteced1 image_eqI)+)[3]
next
  show  ( b  f ` A  Renaming (P b) f)   (Renaming ( a  A  P (f a)) f)
    apply (simp add: F_Renaming F_Mprefix D_Mprefix, safe, simp_all)
      apply (auto simp add: vimage_def image_def, insert hd_map_EvExt, fastforce)[1]
     apply (rule_tac x = ev xa # s1 in exI, simp,
            metis hd_map hd_map_EvExt list.collapse list.discI list.sel(1))
  proof goal_cases
    case (1 a b xa aa s1 s2)
    have s1  𝒟 (P (f xa))
      apply (rule "1"(1)[rule_format, of ev xa # s1 s2, simplified])
      by (simp_all add: "1"(4, 6, 7)) 
         (metis "1"(2, 3, 8) hd_map_EvExt list.collapse list.distinct(1) list.sel(1) list.simps(9))
    with s1  𝒟 (P (f xa)) show ?case by blast
  qed
next
  show 𝒟 (Renaming ( a  A  P (f a)) f)  𝒟 ( b  f ` A  Renaming (P b) f)
    apply (auto simp add: D_Mprefix D_Renaming hd_map_EvExt)
    by (rule_tac x = tl s1 in exI, simp add: map_tl tickFree_tl)
next
  show 𝒟 ( b  f ` A  Renaming (P b) f)  𝒟 (Renaming ( a  A  P (f a)) f)
    apply (auto simp add: D_Mprefix D_Renaming)
    by (rule_tac x = ev xb # s1 in exI, simp, rule_tac x = s2 in exI, simp)
       (metis EvExt_def event.case(1) list.collapse o_apply)
qed



lemma Renaming_Mprefix_inj_on:
  Renaming (Mprefix A P) f =  b  f ` A  Renaming (P (THE a. a  A  f a = b)) f 
  if inj_on_f: inj_on f A
  apply (subst Renaming_Mprefix[symmetric])
  apply (intro arg_cong[where f = λQ. Renaming Q f] mono_Mprefix_eq)
  by (metis that the_inv_into_def the_inv_into_f_f)


corollary Renaming_Mprefix_inj:
  Renaming (Mprefix A P) f =  b  f ` A  Renaming (P (THE a. f a = b)) f if inj_f: inj f
  apply (subst Renaming_Mprefix_inj_on, metis inj_eq inj_onI that)
  apply (rule mono_Mprefix_eq[rule_format])
  by (metis imageE inj_eq[OF inj_f])



text ‹A smart application (as termf is of course injective on the singleton term{a})›

corollary Renaming_prefix: Renaming (a  P) f = (f a  Renaming P f)
  unfolding write0_def by (simp add: Renaming_Mprefix_inj_on)

(* TODO: write corollaries on read and write *)



lemma Renaming_Mndetprefix: Renaming ( a  A  P (f a)) f =  b  f ` A  Renaming (P b) f
  apply (cases A = {}, simp add: Renaming_STOP)
  by (subst Process_eq_spec)
     (auto simp add: F_Renaming F_Mndetprefix D_Renaming D_Mndetprefix Renaming_prefix[symmetric])


corollary Renaming_Mndetprefix_inj_on:
  Renaming (Mndetprefix A P) f =  b  f ` A  Renaming (P (THE a. a  A  f a = b)) f 
  if inj_on_f: inj_on f A
  apply (subst Renaming_Mndetprefix[symmetric])
  apply (intro arg_cong[where f = λQ. Renaming Q f] mono_Mndetprefix_eq)
  by (metis that the_inv_into_def the_inv_into_f_f)
  


corollary Renaming_Mndetprefix_inj:
  Renaming (Mndetprefix A P) f =  b  f ` A   Renaming (P (THE a. f a = b)) f 
  if inj_f: inj f
  apply (subst Renaming_Mndetprefix_inj_on, metis inj_eq inj_onI that)
  apply (rule mono_Mndetprefix_eq[rule_format])
  by (metis imageE inj_eq[OF inj_f])






lemma Renaming_Seq: Renaming (P ; Q) f = Renaming P f ; Renaming Q f
proof (subst Process_eq_spec, intro conjI impI subset_antisym)
  show  (Renaming (P ; Q) f)   (Renaming P f ; Renaming Q f)
    apply (simp add: F_Seq D_Seq F_Renaming D_Renaming T_Renaming, safe;
           auto simp add: EvExt_tF append_single_T_imp_tickFree)
          apply (rule_tac x = s1 in exI)
          apply (metis Diff_insert_absorb Diff_single_insert anteced_EvExt_diff_tick
                       insert_absorb insert_absorb2 is_processT4 subset_insertI)
         apply (rule_tac x = t1 @ t2 in exI, metis map_EvExt_tick map_append)
        apply (metis map_EvExt_tick map_append)
       apply (metis NF_ND)
      apply (metis EvExt_ftF front_tickFree_mono map_append nonTickFree_n_frontTickFree
                   non_tickFree_tick process_charn tickFree_Nil)
     apply (rule_tac x = t1 @ t2 in exI)
    by (metis map_EvExt_tick map_append)+
next
  show  (Renaming P f ; Renaming Q f)   (Renaming (P ; Q) f)
  proof ((simp add: F_Seq D_Seq F_Renaming D_Renaming T_Renaming subset_iff, safe; auto), 
         goal_cases)
    case (1 Y s1)
    then show ?case
      apply (rule_tac x = s1 in exI, safe; simp add: EvExt_tF)
      by (metis (no_types, lifting) Diff_insert_absorb anteced_EvExt_diff_tick insert_Diff 
                                    insert_absorb insert_iff tick_elem_anteced1)
  next
    case (2 Y t1 t1a s1)
    then show ?case 
      apply (rule_tac x = butlast t1a @ s1 in exI)
      by (metis (no_types, opaque_lifting) EvExt_tF T_nonTickFree_imp_decomp butlast_snoc 
                                           map_append map_butlast non_tickFree_tick tickFree_append)
  next
    case (3 Y t1 t1a s1 s2)
    have butlast t1a @ s1  𝒟 P  
          (t1. t1 @ [tick]  𝒯 P  (t2. butlast t1a @ s1 = t1 @ t2  t2  𝒟 Q))
      apply (rule "3"(1)[rule_format, of butlast t1a @ s1, rotated 2, OF "3"(5)])
      using "3"(2) "3"(4) front_tickFree_butlast is_processT2_TR tickFree_append apply blast
      by (metis "3"(3) append.assoc butlast_snoc map_append map_butlast)
    then show ?case 
      by (metis "3"(2, 3, 6) EvExt_tF T_nonTickFree_imp_decomp snoc_eq_iff_butlast tickFree_butlast)
  next
    case (4 Y t1 t1a t2a s1)
    have (if t2a = [] then butlast t1a else t1a)  𝒟 P  
          (t1. t1 @ [tick]  𝒯 P  
                (t2. (if t2a = [] then butlast t1a else t1a) = t1 @ t2  t2  𝒟 Q))
      apply (rule "4"(1)[rule_format, of _ butlast t2a @ map (EvExt f) s1])
      using "4"(2) front_tickFree_butlast tickFree_implies_front_tickFree apply fastforce
       apply (auto, metis "4"(4) append.right_neutral butlast_snoc map_butlast, 
                    metis "4"(4) butlast_append butlast_snoc)
      by (metis "4"(3, 6) EvExt_ftF front_tickFree_append front_tickFree_butlast is_processT2)
    then show ?case
      by (metis "4"(2, 4, 5) EvExt_tF append.right_neutral tickFree_Cons tickFree_append)
  next
    case (5 Y t1 t1a t2a s1 s2)
    have (if t2a = [] then butlast t1a else t1a)  𝒟 P  
          (t1. t1 @ [tick]  𝒯 P  
                (t2. (if t2a = [] then butlast t1a else t1a) = t1 @ t2  t2  𝒟 Q))
      apply (rule "5"(1)[rule_format, of _ butlast t2a @ map (EvExt f) s1 @ s2])
      using "5"(2) tickFree_butlast apply fastforce
       apply (auto, metis "5"(4) append.right_neutral butlast_snoc map_butlast, 
                    metis "5"(4) butlast_append butlast_snoc)
      by (metis "5"(3, 6, 7) EvExt_tF front_tickFree_append front_tickFree_butlast)
    then show ?case
      by (metis "5"(2, 4, 5) EvExt_tF append_Nil2 non_tickFree_tick tickFree_append)
  qed
next
  show 𝒟 (Renaming (P ; Q) f)  𝒟 (Renaming P f ; Renaming Q f)
    apply (auto simp add: D_Seq D_Renaming T_Renaming)
    by (metis map_EvExt_tick map_append)
next
  show 𝒟 (Renaming P f ; Renaming Q f)  𝒟 (Renaming (P ; Q) f)
    apply (auto simp add: D_Seq D_Renaming T_Renaming)
     apply (rule_tac x = butlast t1a @ s1 in exI, auto,
            metis append_butlast_last_id append_single_T_imp_tickFree butlast.simps(1) tickFree_Nil)
     apply (rule_tac x = s2 in exI, auto, metis butlast_snoc map_butlast,
            metis EvExt_tF T_nonTickFree_imp_decomp snoc_eq_iff_butlast tickFree_butlast)
    apply (rule_tac x = t1a in exI, simp)
    apply (rule_tac x = butlast t2a @ map (EvExt f) s1 @ s2 in exI, auto)
     apply (meson EvExt_tF front_tickFree_append front_tickFree_butlast)
    by (metis EvExt_tF butlast_append butlast_snoc non_tickFree_tick tickFree_append)
qed


(* TODO: Renaming of Hiding and Renaming of Sync *)







  




(* ************************************************************************* *)
(* 	                                                    								     *)
(* Setup for rewriting							                                         *)
(* 									                                                         *)
(* ************************************************************************* *)

lemmas Sync_rules =  prefix_Sync2 
                     read_read_Sync read_read_non_Sync 
                     write_read_Sync write_read_non_Sync 
                     write0_read_non_Sync 
                     write0_write_non_Sync

lemmas Hiding_rules = no_Hiding_read no_Hiding_write Hiding_write Hiding_write0

lemmas mono_rules = mono_read_ref mono_write_ref mono_write0_ref

end