Theory Weak_Early_Sim_Pres

(* 
   Title: The pi-calculus   
   Author/Maintainer: Jesper Bengtson (jebe.dk), 2012
*)
theory Weak_Early_Sim_Pres
  imports Weak_Early_Sim
begin

lemma tauPres:
  fixes P    :: pi
  and   Q    :: pi
  and   Rel  :: "(pi × pi) set"
  and   Rel' :: "(pi × pi) set"

  assumes PRelQ: "(P, Q) ∈ Rel"

  shows "τ.(P) ↝<Rel> τ.(Q)"
proof(induct rule: simCases)
  case(Bound Q' a x)
  have "τ.(Q) ⟼a<νx> ≺ Q'" by fact
  hence False by(induct rule: tauCases', auto)
  thus ?case by simp
next
  case(Free Q' α)
  have "τ.(Q) ⟼(α ≺ Q')" by fact
  thus ?case
  proof(induct rule: tauCases', auto simp only: pi.inject residual.inject)
    have "τ.(P) ⟹^ τ ≺ P" by(rule Tau)
    with PRelQ show "∃P'. τ.(P) ⟹^τ ≺ P' ∧ (P', Q) ∈ Rel" by blast
  qed
qed

lemma inputPres:
  fixes P    :: pi
  and   x    :: name
  and   Q    :: pi
  and   a    :: name
  and   Rel  :: "(pi × pi) set"

  assumes PRelQ: "∀y. (P[x::=y], Q[x::=y]) ∈ Rel"
  and     Eqvt: "eqvt Rel"

  shows "a<x>.P ↝<Rel> a<x>.Q"
using Eqvt
proof(induct rule: simCasesCont[where C="(x, a, P, Q)"])
  case(Bound b y Q')
  from ‹y ♯ (x, a, P, Q)› have "y ≠ x" "y ≠ a" "y ♯ P" "y ♯ Q" by simp+
  from ‹a<x>.Q ⟼b<νy> ≺ Q'› ‹y ≠ a› ‹y ≠ x› ‹y ♯ Q› show ?case
    by(erule_tac inputCases') auto
next
  case(Free α Q')
  from ‹a<x>.Q ⟼ α ≺ Q'›
  show ?case
  proof(induct rule: inputCases)
    case(cInput u)
    have "a<x>.P ⟹^(a<u>) ≺ P[x::=u]"
      by(rule Input)
    moreover from PRelQ have "(P[x::=u], Q[x::=u]) ∈ Rel" by auto
    ultimately show ?case by blast
  qed
qed

lemma outputPres:
  fixes P    :: pi
  and   Q    :: pi
  and   a    :: name
  and   b    :: name
  and   Rel  :: "(pi × pi) set"

  assumes PRelQ: "(P, Q) ∈ Rel"

  shows "a{b}.P ↝<Rel> a{b}.Q"
proof(induct rule: simCases)
  case(Bound Q' c x)
  have "a{b}.Q ⟼c<νx> ≺ Q'" by fact
  hence False by(induct rule: outputCases', auto)
  thus ?case by simp
next
  case(Free Q' α)
  have "a{b}.Q ⟼α ≺ Q'" by fact
  thus "∃P'. a{b}.P ⟹^ α ≺ P' ∧ (P', Q') ∈ Rel"
  proof(induct rule: outputCases', auto simp add: pi.inject residual.inject)
    have "a{b}.P ⟹^ a[b] ≺ P" by(rule Output)
    with PRelQ show "∃P'. a{b}.P ⟹^ a[b] ≺ P' ∧ (P', Q) ∈ Rel" by blast
  qed
qed

lemma matchPres:
  fixes P    :: pi
  and   Q    :: pi
  and   a    :: name
  and   b    :: name
  and   Rel  :: "(pi × pi) set"
  and   Rel' :: "(pi × pi) set"

  assumes PSimQ: "P ↝<Rel> Q"
  and     RelRel': "Rel ⊆ Rel'"
  and     RelStay: "⋀R S c. (R, S) ∈ Rel ⟹ ([c⌢c]R, S) ∈ Rel"

  shows "[a⌢b]P ↝<Rel'> [a⌢b]Q"
proof(induct rule: simCases)
  case(Bound Q' c x)
  have "x ♯ [a⌢b]P" by fact
  hence xFreshP: "(x::name) ♯ P" by simp
  have "[a⌢b]Q ⟼c<νx> ≺ Q'" by fact
  thus ?case
  proof(induct rule: matchCases)
    case Match
    have "Q ⟼c<νx> ≺ Q'" by fact
    with PSimQ xFreshP obtain P' where PTrans: "P ⟹c<νx> ≺ P'"
                                   and P'RelQ': "(P', Q') ∈ Rel"
      by(blast dest: simE)
    from PTrans have "[a⌢a]P ⟹c<νx> ≺ P'" by(rule Weak_Early_Step_Semantics.Match)
    moreover from P'RelQ' RelRel' have "(P', Q') ∈ Rel'" by blast
    ultimately show ?case by blast
  qed
next
  case(Free Q' α)
  have "[a⌢b]Q ⟼α ≺ Q'" by fact
  thus ?case
  proof(induct rule: matchCases)
    case Match
    have "Q ⟼ α ≺ Q'" by fact
    with PSimQ obtain P' where "P ⟹^α ≺ P'" and "(P', Q') ∈ Rel"
      by(blast dest: simE)
    thus ?case
    proof(induct rule: transitionCases)
      case Step
      have "P ⟹α ≺ P'" by fact
      hence "[a⌢a]P ⟹α ≺ P'" by(rule Weak_Early_Step_Semantics.Match)
      with RelRel' ‹(P', Q') ∈ Rel› show ?case by(force simp add: weakFreeTransition_def)
    next
      case Stay
      have "[a⌢a]P ⟹^τ ≺ [a⌢a]P" by(simp add: weakFreeTransition_def)
      moreover from ‹(P, Q') ∈ Rel› have "([a⌢a]P, Q') ∈ Rel" by(blast intro: RelStay)
      ultimately show ?case using RelRel' by blast
    qed
  qed
qed

lemma mismatchPres:
  fixes P    :: pi
  and   Q    :: pi
  and   a    :: name
  and   b    :: name
  and   Rel  :: "(pi × pi) set"
  and   Rel' :: "(pi × pi) set"

  assumes PSimQ: "P ↝<Rel> Q"
  and     RelRel': "Rel ⊆ Rel'"
  and     RelStay: "⋀R S c d. ⟦(R, S) ∈ Rel; c ≠ d⟧ ⟹ ([c≠d]R, S) ∈ Rel"

  shows "[a≠b]P ↝<Rel'> [a≠b]Q"
proof(induct rule: simCases)
  case(Bound Q' c x)
  have "x ♯ [a≠b]P" by fact
  hence xFreshP: "(x::name) ♯ P" by simp
  have "[a≠b]Q ⟼c<νx> ≺ Q'" by fact
  thus ?case
  proof(induct rule: mismatchCases)
    case Mismatch
    have aineqb: "a ≠ b" by fact
    have "Q ⟼c<νx> ≺ Q'" by fact
    with PSimQ xFreshP obtain P' where PTrans: "P ⟹c<νx> ≺ P'"
                                   and P'RelQ': "(P', Q') ∈ Rel"
      by(blast dest: simE)
    from PTrans aineqb have "[a≠b]P ⟹c<νx> ≺ P'" by(rule Weak_Early_Step_Semantics.Mismatch)
    moreover from P'RelQ' RelRel' have "(P', Q') ∈ Rel'" by blast
    ultimately show ?case by blast
  qed
next
  case(Free Q' α)
  have "[a≠b]Q ⟼α ≺ Q'" by fact
  thus ?case
  proof(induct rule: mismatchCases)
    case Mismatch
    have aineqb: "a ≠ b" by fact
    have "Q ⟼ α ≺ Q'" by fact
    with PSimQ obtain P' where "P ⟹^α ≺ P'" and "(P', Q') ∈ Rel"
      by(blast dest: simE)
    thus ?case
    proof(induct rule: transitionCases)
      case Step
      have "P ⟹α ≺ P'" by fact
      hence "[a≠b]P ⟹α ≺ P'" using aineqb by(rule Weak_Early_Step_Semantics.Mismatch)
      with RelRel' ‹(P', Q') ∈ Rel› show ?case by(force simp add: weakFreeTransition_def)
    next
      case Stay
      have "[a≠b]P ⟹^τ ≺ [a≠b]P" by(simp add: weakFreeTransition_def)
      moreover from ‹(P, Q') ∈ Rel› aineqb have "([a≠b]P, Q') ∈ Rel" by(blast intro: RelStay)
      ultimately show ?case using RelRel' by blast
    qed
  qed
qed

lemma parCompose:
  fixes P     :: pi
  and   Q     :: pi
  and   R     :: pi
  and   S     :: pi
  and   Rel   :: "(pi × pi) set"
  and   Rel'  :: "(pi × pi) set"
  and   Rel'' :: "(pi × pi) set"
  
  assumes PSimQ:    "P ↝<Rel> Q"
  and     RSimT:    "R ↝<Rel'> S"
  and     PRelQ:    "(P, Q) ∈ Rel"
  and     RRel'T:   "(R, S) ∈ Rel'"
  and     Par:      "⋀P' Q' R' S'. ⟦(P', Q') ∈ Rel; (R', S') ∈ Rel'⟧ ⟹ (P' ∥ R', Q' ∥ S') ∈ Rel''"
  and     Res:      "⋀T U x. (T, U) ∈ Rel'' ⟹ (<νx>T, <νx>U) ∈ Rel''"

  shows "P ∥ R ↝<Rel''> Q ∥ S"
proof -
  show ?thesis
  proof(induct rule: simCases)
    case(Bound Q' a x)
    have "x ♯ P ∥ R" by fact
    hence xFreshP: "x ♯ P" and xFreshR: "x ♯ R" by simp+
    have "Q ∥ S ⟼a<νx> ≺ Q'" by fact
    thus ?case
    proof(induct rule: parCasesB)
      case(cPar1 Q')
      have QTrans: "Q ⟼ a<νx> ≺ Q'" and xFreshT: "x ♯ S" by fact+
      from xFreshP PSimQ QTrans obtain P' where PTrans:"P ⟹a<νx> ≺ P'"
                                            and P'RelQ': "(P', Q') ∈ Rel"
        by(blast dest: simE)
      from PTrans xFreshR have "P ∥ R ⟹a<νx> ≺ (P' ∥ R)" by(rule Weak_Early_Step_Semantics.Par1B)
      moreover from P'RelQ' RRel'T have "(P' ∥ R, Q' ∥ S) ∈ Rel''" by(rule Par)
      ultimately show ?case by blast
    next
      case(cPar2 S')
      have STrans: "S ⟼ a<νx> ≺ S'" and xFreshQ: "x ♯ Q" by fact+
      from xFreshR RSimT STrans obtain R' where RTrans:"R ⟹a<νx> ≺ R'"
                                            and R'Rel'T': "(R', S') ∈  Rel'"
        by(blast dest: simE)
      from RTrans xFreshP xFreshR have ParTrans: "P ∥ R ⟹a<νx> ≺ (P ∥ R')"
        by(blast intro: Weak_Early_Step_Semantics.Par2B)
      moreover from PRelQ R'Rel'T' have "(P ∥ R', Q ∥  S') ∈ Rel''" by(rule Par)
      ultimately show ?case by blast
    qed
  next
    case(Free QT' α)
    have "Q ∥ S ⟼ α ≺ QT'" by fact
    thus ?case
    proof(induct rule: parCasesF[of _ _ _ _ _ "(P, R)"])
      case(cPar1 Q')
      have "Q ⟼ α ≺ Q'" by fact
      with PSimQ obtain P' where PTrans: "P ⟹^ α ≺ P'" and PRel: "(P', Q') ∈ Rel"
        by(blast dest: simE)
      from PTrans have Trans: "P ∥ R ⟹^ α ≺ P' ∥ R" by(rule Weak_Early_Semantics.Par1F)
      moreover from PRel RRel'T have "(P' ∥ R, Q' ∥ S) ∈ Rel''" by(blast intro: Par)
      ultimately show ?case by blast
    next
      case(cPar2 S')
      have "S ⟼ α ≺ S'" by fact
      with RSimT obtain R' where RTrans: "R ⟹^ α ≺ R'" and RRel: "(R', S') ∈ Rel'"
        by(blast dest: simE)
      from RTrans have Trans: "P ∥ R ⟹^ α ≺ P ∥ R'" by(rule Weak_Early_Semantics.Par2F)
      moreover from PRelQ RRel have "(P ∥ R', Q ∥ S') ∈ Rel''" by(blast intro: Par)
      ultimately show ?case by blast
    next
      case(cComm1 Q' S' a b)
      have QTrans: "Q ⟼ a<b> ≺ Q'" and STrans: "S ⟼ a[b] ≺ S'" by fact+

      from PSimQ QTrans obtain P' where PTrans: "P ⟹a<b> ≺ P'"
                                    and P'RelQ': "(P', Q') ∈ Rel"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      
      from RSimT STrans obtain R' where RTrans: "R ⟹a[b] ≺ R'"
                                    and RRel: "(R', S') ∈ Rel'"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      
      from PTrans RTrans have "P ∥ R ⟹τ ≺ P' ∥ R'" by(rule Weak_Early_Step_Semantics.Comm1)
      hence "P ∥ R ⟹^τ ≺ P' ∥ R'" 
        by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)

      moreover from P'RelQ' RRel have "(P' ∥ R', Q' ∥ S') ∈ Rel''" by(rule Par)
      ultimately show ?case by blast
    next
      case(cComm2 Q' S' a b)
      have QTrans: "Q ⟼a[b] ≺ Q'" and STrans: "S ⟼a<b> ≺ S'" by fact+
      
      from PSimQ QTrans obtain P' where PTrans: "P ⟹a[b] ≺ P'"
                                    and PRel: "(P', Q') ∈ Rel"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      
      from RSimT STrans obtain R' where RTrans: "R ⟹a<b> ≺ R'"
                                   and R'Rel'T': "(R', S') ∈ Rel'"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      
      from PTrans RTrans have "P ∥ R ⟹τ ≺ P' ∥ R'" by(rule Weak_Early_Step_Semantics.Comm2)
      hence "P ∥ R ⟹^τ ≺ P' ∥ R'" 
        by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)
      moreover from PRel R'Rel'T' have "(P' ∥ R', Q' ∥ S') ∈ Rel''" by(rule Par)
      ultimately show ?case by blast
    next
      case(cClose1 Q' S' a x)
      have QTrans: "Q ⟼a<x> ≺ Q'" and STrans: "S ⟼a<νx> ≺ S'" by fact+
      have "x ♯ (P, R)" by fact
      hence xFreshP: "x ♯ P" and xFreshR: "x ♯ R" by(simp add: fresh_prod)+
      
      from PSimQ QTrans obtain P' where PTrans: "P ⟹a<x> ≺ P'"
                                    and P'RelQ': "(P', Q') ∈ Rel"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      
      from RSimT STrans xFreshR obtain R' where RTrans: "R ⟹a<νx> ≺ R'" 
                                            and R'Rel'T': "(R', S') ∈ Rel'"
        by(blast dest: simE)
       
      from PTrans RTrans xFreshP have Trans: "P ∥ R ⟹τ ≺ <νx>(P' ∥ R')"
        by(rule Weak_Early_Step_Semantics.Close1)
      hence "P ∥ R ⟹^τ ≺ <νx>(P' ∥ R')" 
        by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)
      moreover from P'RelQ' R'Rel'T' have "(<νx>(P' ∥ R'), <νx>(Q' ∥ S')) ∈ Rel''"
        by(blast intro: Par Res)
      ultimately show ?case by blast
    next
      case(cClose2 Q' S' a x)
      have QTrans: "Q ⟼a<νx> ≺ Q'" and STrans: "S ⟼a<x> ≺ S'" by fact+
      have "x ♯ (P, R)" by fact
      hence xFreshR: "x ♯ R" and xFreshP: "x ♯ P" by(simp add: fresh_prod)+

      from PSimQ QTrans xFreshP obtain P' where PTrans: "P ⟹a<νx> ≺ P'"
                                            and P'RelQ': "(P', Q') ∈ Rel"
        by(blast dest: simE)
      
      from RSimT STrans obtain R' where RTrans: "R ⟹a<x> ≺ R'"
                                    and R'Rel'T': "(R', S') ∈ Rel'"
        by(fastforce dest: simE simp add: weakFreeTransition_def)
      from PTrans RTrans xFreshR have Trans: "P ∥ R ⟹τ ≺ <νx>(P' ∥ R')"
        by(rule Weak_Early_Step_Semantics.Close2)
      hence "P ∥ R ⟹^τ ≺ <νx>(P' ∥ R')" 
        by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)
      moreover from P'RelQ' R'Rel'T' have "(<νx>(P' ∥ R'), <νx>(Q' ∥ S')) ∈ Rel''"
        by(blast intro: Par Res)
      ultimately show ?case by blast
    qed
  qed
qed

lemma parPres:
  fixes P   :: pi
  and   Q   :: pi
  and   R   :: pi
  and   a   :: name
  and   Rel :: "(pi × pi) set"
  and   Rel' :: "(pi × pi) set"
  
  assumes PSimQ:    "P ↝<Rel> Q"
  and     PRelQ:    "(P, Q) ∈ Rel"
  and     Par:      "⋀S T U. (S, T) ∈ Rel ⟹ (S ∥ U, T ∥ U) ∈ Rel'"
  and     Res:      "⋀S T x. (S, T) ∈ Rel' ⟹ (<νx>S, <νx>T) ∈ Rel'"

  shows "P ∥ R ↝<Rel'> Q ∥ R"
proof -
  note PSimQ 
  moreover have RSimR: "R ↝<Id> R" by(auto intro: reflexive)
  moreover note PRelQ moreover have "(R, R) ∈ Id" by auto
  moreover from Par have "⋀P Q R T. ⟦(P, Q) ∈ Rel; (R, T) ∈ Id⟧ ⟹ (P ∥ R, Q ∥ T) ∈ Rel'"
    by auto
  ultimately show ?thesis using Res by(rule parCompose)
qed

lemma resPres:
  fixes P    :: pi
  and   Q    :: pi
  and   Rel  :: "(pi × pi) set"
  and   x    :: name
  and   Rel' :: "(pi × pi) set"

  assumes PSimQ: "P ↝<Rel> Q"
  and     ResRel: "⋀R S y. (R, S) ∈ Rel ⟹ (<νy>R, <νy>S) ∈ Rel'"
  and     RelRel': "Rel ⊆ Rel'"
  and     EqvtRel: "eqvt Rel"
  and     EqvtRel': "eqvt Rel'"

  shows "<νx>P ↝<Rel'> <νx>Q"
proof -
  from EqvtRel' show ?thesis
  proof(induct rule: simCasesCont[where C="(P, x)"])
    case(Bound a y Q')
    have Trans: "<νx>Q ⟼a<νy> ≺ Q'" by fact
    have "y ♯ (P, x)" by fact
    hence yineqx: "y ≠ x" and yFreshP: "y ♯ P" by(simp add: fresh_prod)+
    from Trans yineqx show ?case
    proof(induct rule: resCasesB)
      case(Open Q')
      have QTrans: "Q ⟼a[x] ≺ Q'" and aineqx: "a ≠ x" by fact+

      from PSimQ QTrans obtain P' where PTrans: "P ⟹^a[x] ≺ P'"
                                    and P'RelQ': "(P', Q') ∈ Rel"
        by(blast dest: simE)
      
      from PTrans aineqx have "<νx>P ⟹a<νx> ≺ P'" 
        by(force intro: Weak_Early_Step_Semantics.Open simp add: weakFreeTransition_def)
      with ‹y ♯ P› ‹y ≠ x› have "<νx>P ⟹a<νy> ≺ ([(y, x)] ∙ P')"
        by(force intro: weakTransitionAlpha simp add: abs_fresh name_swap)
      moreover from EqvtRel P'RelQ' RelRel' have "([(y, x)] ∙ P', [(y, x)] ∙ Q') ∈ Rel'"
        by(blast intro: eqvtRelI)
      ultimately show ?case by blast
    next
      case(Res Q')
      have QTrans: "Q ⟼a<νy> ≺ Q'" and xineqa: "x ≠ a" by fact+

      from PSimQ yFreshP QTrans obtain P' where PTrans: "P ⟹a<νy> ≺ P'"
                                            and P'RelQ': "(P', Q') ∈ Rel"
        by(blast dest: simE)
      from PTrans xineqa yineqx yFreshP have ResTrans: "<νx>P ⟹a<νy> ≺ (<νx>P')"
        by(blast intro: Weak_Early_Step_Semantics.ResB)
      moreover from P'RelQ' have "((<νx>P'), (<νx>Q')) ∈ Rel'"
        by(rule ResRel)
      ultimately show ?case by blast
    qed
  next
    case(Free α Q')
    have QTrans: "<νx>Q ⟼ α ≺ Q'" by fact
    have "∃c::name. c ♯ (P, Q, Q', α)" by(blast intro: name_exists_fresh)
    then obtain c::name where cFreshQ: "c ♯ Q" and cFreshAlpha: "c ♯ α" and cFreshQ': "c ♯ Q'" and cFreshP: "c ♯ P"
      by(force simp add: fresh_prod)
    from cFreshP have "<νx>P = <νc>([(x, c)] ∙ P)" by(simp add: alphaRes)
    moreover have "∃P'.<νc>([(x, c)] ∙ P) ⟹^ α ≺ P' ∧ (P', Q') ∈ Rel'"
    proof -
      from QTrans cFreshQ have "<νc>([(x, c)] ∙ Q) ⟼α ≺ Q'" by(simp add: alphaRes)
      moreover have "c ♯ α" by(rule cFreshAlpha)
      moreover from PSimQ EqvtRel have "([(x, c)] ∙ P) ↝<Rel> ([(x, c)] ∙ Q)"
        by(blast intro: eqvtI)
      ultimately show ?thesis
        apply(induct rule: resCasesF, auto simp add: residual.inject pi.inject name_abs_eq)
        by(blast intro: ResF ResRel dest: simE)
    qed

    ultimately show ?case by force
  qed
qed

lemma resChainI:
  fixes P   :: pi
  and   Q   :: pi
  and   Rel :: "(pi × pi) set"
  and   lst :: "name list"

  assumes eqvtRel: "eqvt Rel"
  and     Res:     "⋀R S y. (R, S) ∈ Rel ⟹ (<νy>R, <νy>S) ∈ Rel"
  and     PRelQ:   "P ↝<Rel> Q"

  shows "(resChain lst) P ↝<Rel> (resChain lst) Q"
proof -
  show ?thesis
  proof(induct lst) (* Base case *)
    from PRelQ show "resChain [] P ↝<Rel> resChain [] Q" by simp
  next (* Inductive step *)
    fix a lst
    assume IH: "(resChain lst P) ↝<Rel> (resChain lst Q)"
    moreover from Res have "⋀P Q a. (P, Q) ∈ Rel ⟹ (<νa>P, <νa>Q) ∈ Rel"
      by simp
    moreover have "Rel ⊆ Rel" by simp
    ultimately have "<νa>(resChain lst P) ↝<Rel> <νa>(resChain lst Q)" using eqvtRel
      by(rule_tac resPres)
    thus "resChain (a # lst) P ↝<Rel> resChain (a # lst) Q"
      by simp
  qed
qed

lemma bangPres:
  fixes P    :: pi
  and   Q    :: pi
  and   Rel  :: "(pi × pi) set"
 
  assumes PRelQ:       "(P, Q) ∈ Rel"
  and     Sim:         "⋀R S. (R, S) ∈ Rel ⟹ R ↝<Rel> S"

  and     ParComp:     "⋀R S T U. ⟦(R, S) ∈ Rel; (T, U) ∈ Rel'⟧ ⟹ (R ∥ T, S ∥ U) ∈ Rel'"
  and     Res:         "⋀R S x. (R, S) ∈ Rel' ⟹ (<νx>R, <νx>S) ∈ Rel'"

  and     RelStay:        "⋀R S. (R ∥ !R, S) ∈ Rel' ⟹ (!R, S) ∈ Rel'"
  and     BangRelRel': "(bangRel Rel) ⊆ Rel'"
  and     eqvtRel':    "eqvt Rel'"

  shows "!P ↝<Rel'> !Q"
proof -
  let ?Sim = "λP Rs. (∀a x Q'. Rs = a<νx> ≺ Q' ⟶ x ♯ P ⟶ (∃P'. P ⟹a<νx> ≺ P' ∧ (P', Q') ∈ Rel')) ∧
                     (∀α Q'. Rs = α ≺ Q' ⟶ (∃P'. P ⟹^α ≺ P' ∧ (P', Q') ∈ Rel'))"
  {
    fix Rs P
    assume "!Q ⟼ Rs" and "(P, !Q) ∈ bangRel Rel"
    hence "?Sim P Rs" using PRelQ
    proof(nominal_induct avoiding: P rule: bangInduct)
      case(Par1B a x Q')
      have QTrans: "Q ⟼a<νx> ≺ Q'" and xFreshQ: "x ♯ Q" by fact+
      have "(P, Q ∥ !Q) ∈ bangRel Rel" and "x ♯ P" by fact+
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelT: "(R, !Q) ∈ bangRel Rel" by fact+
        have "x ♯ P ∥ R" by fact
        hence xFreshP: "x ♯ P" and xFreshR: "x ♯ R" by simp+
        from PRelQ have PSimQ: "P ↝<Rel> Q" by(rule Sim)
        from ‹x ♯ P› ‹x ♯ Q› show ?case
        proof(auto simp add: residual.inject alpha' name_fresh_fresh)
          from PSimQ QTrans xFreshP obtain P' where PTrans: "P ⟹a<νx> ≺ P'"
                                                and P'RelQ': "(P', Q') ∈ Rel"
            by(blast dest: simE)
          from PTrans xFreshR have "P ∥ R ⟹a<νx>≺ (P' ∥ R)"
            by(rule Weak_Early_Step_Semantics.Par1B)
          moreover from P'RelQ' RBangRelT BangRelRel' have "(P' ∥ R, Q' ∥ !Q) ∈ Rel'"
            by(blast intro: Rel.BRPar)
          ultimately show "∃P'. P ∥ R ⟹a<νx> ≺ P' ∧ (P', Q' ∥ !Q) ∈ Rel'" by blast
        next
          fix y
          assume "(y::name) ♯ Q'" and "y ♯ P" and "y ♯ R"
          from QTrans ‹y ♯ Q'› have "Q ⟼a<νy> ≺ ([(x, y)] ∙ Q')" by(simp add: alphaBoundOutput)
          with PSimQ ‹y ♯ P› obtain P' where PTrans: "P ⟹a<νy> ≺ P'"
                                         and P'RelQ': "(P', [(x, y)] ∙ Q') ∈ Rel"
            by(blast dest: simE)
          from PTrans ‹y ♯ R› have "P ∥ R ⟹a<νy>≺ (P' ∥ R)" by(rule Weak_Early_Step_Semantics.Par1B)
          moreover from P'RelQ' RBangRelT BangRelRel' have "(P' ∥ R, ([(y, x)] ∙ Q') ∥ !Q) ∈ Rel'"
            by(fastforce intro: Rel.BRPar simp add: name_swap) 
          ultimately show "∃P'. P ∥ R ⟹a<νy> ≺ P' ∧ (P', ([(y, x)] ∙ Q') ∥ !Q) ∈ Rel'" by blast
        qed
      qed
    next
      case(Par1F α Q' P)
      have QTrans: "Q ⟼α ≺ Q'" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" by fact
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        show ?case
        proof(auto simp add: residual.inject)
          from PRelQ have "P ↝<Rel> Q" by(rule Sim)
          with QTrans obtain P' where PTrans: "P ⟹^α ≺ P'" and P'RelQ': "(P', Q') ∈ Rel"
            by(blast dest: simE)

          from PTrans have "P ∥ R ⟹^α ≺ P' ∥ R" by(rule Weak_Early_Semantics.Par1F)
          moreover from P'RelQ' RBangRelQ have "(P' ∥ R, Q' ∥ !Q) ∈ bangRel Rel"
            by(rule Rel.BRPar)
          ultimately show "∃P'. P ∥ R ⟹^α ≺ P' ∧ (P', Q' ∥ !Q) ∈ Rel'" using BangRelRel' by blast
        qed
      qed
    next
      case(Par2B a x Q' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (a<νx> ≺ Q')" by simp
      have xFreshQ: "x ♯ Q" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" and "x ♯ P" by fact+
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        have "x ♯ P ∥ R" by fact
        hence xFreshP: "x ♯ P" and xFreshR: "x ♯ R" by simp+
        show ?case using ‹x ♯ Q›
        proof(auto simp add: residual.inject alpha' name_fresh_fresh)
          from IH RBangRelQ have "?Sim R (a<νx> ≺ Q')" by blast
          with xFreshR obtain R' where RTrans: "R ⟹a<νx> ≺ R'" and R'BangRelQ': "(R', Q') ∈ Rel'"
            by(blast dest: simE)
          from RTrans xFreshP have "P ∥ R ⟹a<νx> ≺ (P ∥ R')"
            by(auto intro: Weak_Early_Step_Semantics.Par2B)
          moreover from PRelQ R'BangRelQ' have "(P ∥ R', Q ∥ Q') ∈ Rel'"
            by(rule ParComp)
          ultimately show "∃P'. P ∥ R ⟹a<νx> ≺ P' ∧ (P', Q ∥ Q') ∈ Rel'" by blast
        next
          fix y
          assume "(y::name) ♯ Q'" and "y ♯ R" and "y ♯ P"
          from IH RBangRelQ have "?Sim R (a<νx> ≺ Q')" by blast
          with ‹y ♯ Q'› have  "?Sim R (a<νy> ≺ ([(x, y)] ∙ Q'))" by(simp add: alphaBoundOutput)
          with ‹y ♯ R›obtain R' where RTrans: "R ⟹a<νy> ≺ R'" and R'BangRelQ': "(R', [(x, y)] ∙ Q') ∈ Rel'"
            by(blast dest: simE)
          from RTrans ‹y ♯ P› have "P ∥ R ⟹a<νy> ≺ (P ∥ R')"
            by(auto intro: Weak_Early_Step_Semantics.Par2B)
          moreover from PRelQ R'BangRelQ' have "(P ∥ R', Q ∥ ([(y, x)] ∙ Q')) ∈ Rel'"
            by(fastforce intro: ParComp simp add: name_swap)
          ultimately show "∃P'. P ∥ R ⟹a<νy> ≺ P' ∧ (P', Q ∥ ([(y, x)] ∙ Q')) ∈ Rel'" by blast
        qed
      qed
    next
      case(Par2F α Q' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (α ≺ Q')" by simp
      have "(P, Q ∥ !Q) ∈ bangRel Rel" by fact
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        show ?case
        proof(auto simp add: residual.inject)
          from RBangRelQ have "?Sim R (α ≺ Q')" by(rule IH)
          then obtain R' where RTrans: "R ⟹^α ≺ R'" and R'RelQ': "(R', Q') ∈ Rel'"
            by(blast dest: simE)
          from RTrans have "P ∥ R ⟹^α ≺ P ∥ R'" by(rule Weak_Early_Semantics.Par2F)
          moreover from PRelQ R'RelQ' have "(P ∥ R', Q ∥ Q') ∈ Rel'" by(rule ParComp)
          ultimately show "∃P'. P ∥ R ⟹^α ≺ P' ∧ (P', Q ∥ Q') ∈ Rel'" by blast
        qed
      qed
    next
      case(Comm1 a Q' b Q'' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (a[b] ≺ Q'')" by simp
      have QTrans: "Q ⟼ a<b> ≺ Q'" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" by fact
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        show ?case
        proof(auto simp add: residual.inject)
          from PRelQ have "P ↝<Rel> Q" by(rule Sim)
          with QTrans obtain P' where PTrans: "P ⟹a<b> ≺ P'" and P'RelQ': "(P', Q') ∈ Rel"
            by(fastforce dest: simE simp add: weakFreeTransition_def)

          from RBangRelQ have "?Sim R (a[b] ≺ Q'')" by(rule IH)
          then obtain R' where RTrans: "R ⟹a[b] ≺ R'"
                           and R'RelQ'': "(R', Q'') ∈ Rel'"
            by(fastforce dest: simE simp add: weakFreeTransition_def)
          from PTrans RTrans have "P ∥ R ⟹τ ≺ (P' ∥ R')"
            by(rule Weak_Early_Step_Semantics.Comm1)
          hence "P ∥ R ⟹τ P' ∥ R'" 
            by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)
          moreover from P'RelQ' R'RelQ'' have "(P' ∥ R', Q' ∥ Q'') ∈ Rel'"
            by(rule ParComp)
          ultimately show "∃P'. (P ∥ R, P') ∈ {(P, P'). P ⟼ τ ≺ P'}* ∧ (P', Q' ∥ Q'') ∈ Rel'"
            by auto
        qed
      qed
    next
      case(Comm2 a b Q' Q'' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (a<b> ≺ Q'')" by simp
      have QTrans: "Q ⟼a[b] ≺ Q'" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" by fact
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        show ?case
        proof(auto simp add: residual.inject)
          from PRelQ have "P ↝<Rel> Q" by(rule Sim)
          with QTrans obtain P' where PTrans: "P ⟹a[b] ≺ P'" and P'RelQ': "(P', Q') ∈ Rel"
            by(fastforce dest: simE simp add: weakFreeTransition_def)

          from RBangRelQ have "?Sim R (a<b> ≺ Q'')" by(rule IH)
          then obtain R' where RTrans: "R ⟹a<b> ≺ R'" and R'BangRelQ'': "(R', Q'') ∈ Rel'"
            by(fastforce dest: simE simp add: weakFreeTransition_def)
        
          from PTrans RTrans have "P ∥ R ⟹τ ≺ (P' ∥ R')"
            by(rule Weak_Early_Step_Semantics.Comm2)
          hence "P ∥ R ⟹τ P' ∥ R'" 
            by(auto simp add: trancl_into_rtrancl dest: Weak_Early_Step_Semantics.tauTransitionChain)
          moreover from P'RelQ' R'BangRelQ'' have "(P' ∥ R', Q' ∥ Q'') ∈ Rel'"
            by(rule ParComp)
          ultimately show "∃P'. (P ∥ R, P') ∈ {(P, P'). P ⟼ τ ≺ P'}* ∧ (P', Q' ∥ Q'') ∈ Rel'" by auto
        qed
      qed
    next
      case(Close1 a x Q' Q'' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (a<νx> ≺ Q'')" by simp
      have QTrans: "Q ⟼ a<x> ≺ Q'" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" and "x ♯ P" by fact+
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        have "x ♯ P ∥ R" by fact
        hence xFreshR: "x ♯ R" and xFreshP: "x ♯ P" by simp+
        show ?case
        proof(auto simp add: residual.inject)
          from PRelQ have "P ↝<Rel> Q" by(rule Sim)
          with QTrans obtain P' where PTrans: "P ⟹a<x> ≺ P'" and P'RelQ': "(P', Q') ∈ Rel"
            by(fastforce dest: simE simp add: weakFreeTransition_def)
          
          from RBangRelQ have "?Sim R (a<νx> ≺ Q'') " by(rule IH)
          with xFreshR obtain R' where RTrans: "R ⟹a<νx> ≺ R'"
                                   and R'RelQ'': "(R', Q'') ∈ Rel'"
            by(blast dest: simE)
        
          from PTrans RTrans xFreshP have "P ∥ R ⟹τ ≺ <νx>(P' ∥ R')"
            by(rule Weak_Early_Step_Semantics.Close1)
          moreover from P'RelQ' R'RelQ'' have "(<νx>(P' ∥ R'), <νx>(Q' ∥ Q'')) ∈ Rel'"
            by(force intro: ParComp Res)
          ultimately show "∃P'. (P ∥ R, P') ∈ {(P, P'). P ⟼ τ ≺ P'}* ∧ (P', <νx>(Q' ∥ Q'')) ∈ Rel'" by auto
        qed
      qed
    next
      case(Close2 a x Q' Q'' P)
      hence IH: "⋀P. (P, !Q) ∈ bangRel Rel ⟹ ?Sim P (a<x> ≺ Q'')" by simp
      have QTrans: "Q ⟼ a<νx> ≺ Q'" by fact
      have "(P, Q ∥ !Q) ∈ bangRel Rel" and "x ♯ P" by fact+
      thus ?case
      proof(induct rule: BRParCases)
        case(BRPar P R)
        have PRelQ: "(P, Q) ∈ Rel" and RBangRelQ: "(R, !Q) ∈ bangRel Rel" by fact+
        have "x ♯ P ∥ R" by fact
        hence xFreshP: "x ♯ P" and xFreshR: "x ♯ R" by simp+
        show ?case
        proof(auto simp add: residual.inject)
          from PRelQ have "P ↝<Rel> Q" by(rule Sim)
          with QTrans xFreshP obtain P' where PTrans: "P ⟹a<νx> ≺ P'"
                                          and P'RelQ': "(P', Q') ∈ Rel"
            by(blast dest: simE)

          from RBangRelQ have "?Sim R (a<x> ≺ Q'')" by(rule IH)
          with xFreshR obtain R' where RTrans: "R ⟹a<x> ≺ R'"
                                       and R'RelQ'': "(R', Q'') ∈ Rel'"
            by(fastforce simp add: weakFreeTransition_def)
          from PTrans RTrans xFreshR have "P ∥ R ⟹τ ≺ <νx>(P' ∥ R')"
            by(rule Weak_Early_Step_Semantics.Close2)
          moreover from P'RelQ' R'RelQ'' have "(<νx>(P' ∥ R'), <νx>(Q' ∥ Q'')) ∈ Rel'"
            by(force intro: ParComp Res)
          ultimately show "∃P'. (P ∥ R, P') ∈ {(P, P'). P ⟼ τ ≺ P'}* ∧ (P', <νx>(Q' ∥ Q'')) ∈ Rel'" by auto
        qed
      qed
    next
      case(Bang Rs)
      hence IH: "⋀P. (P, Q ∥ !Q) ∈ bangRel Rel ⟹ ?Sim P Rs" by simp
      have "(P, !Q) ∈ bangRel Rel" by fact
      thus ?case
      proof(induct rule: BRBangCases)
        case(BRBang P)
        have PRelQ: "(P, Q) ∈ Rel" by fact
        hence "(!P, !Q) ∈ bangRel Rel" by(rule Rel.BRBang)
        with PRelQ have "(P ∥ !P, Q ∥ !Q) ∈ bangRel Rel" by(rule Rel.BRPar)
        hence IH: "?Sim (P ∥ !P) Rs" by(rule IH)
        show ?case
        proof(intro conjI allI impI)
          fix Q' a x
          assume "Rs = a<νx> ≺ Q'" and "x ♯ !P"
          then obtain P' where PTrans: "(P ∥ !P) ⟹a<νx> ≺ P'"
                           and P'RelQ': "(P', Q') ∈ Rel'" using IH
            by(auto simp add: residual.inject)
          from PTrans have "!P ⟹a<νx> ≺ P'"
            by(force intro: Weak_Early_Step_Semantics.Bang simp add: weakFreeTransition_def)
          with P'RelQ' show "∃P'. !P ⟹a<νx> ≺ P' ∧ (P', Q') ∈ Rel'" by blast
        next
          fix Q' α
          assume "Rs = α ≺ Q'"
          then obtain P' where PTrans: "(P ∥ !P) ⟹^α ≺ P'"
                           and P'RelQ': "(P', Q') ∈ Rel'" using IH
            by auto
          from PTrans show "∃P'. !P ⟹^α ≺ P' ∧ (P', Q') ∈ Rel'" using P'RelQ'
          proof(induct rule: transitionCases)
            case Step
            have "P ∥ !P ⟹α ≺ P'" by fact
            hence "!P ⟹α ≺ P'" by(rule Weak_Early_Step_Semantics.Bang)
            with P'RelQ' show ?case by(force simp add: weakFreeTransition_def)
          next
            case Stay
            have "!P ⟹^τ ≺ !P" by(simp add: weakFreeTransition_def)
            moreover assume "(P ∥ !P, Q') ∈ Rel'"
            hence "(!P, Q') ∈ Rel'" by(blast intro: RelStay)
            ultimately show ?case by blast
          qed
        qed
      qed
    qed
  }
  moreover from PRelQ have "(!P, !Q) ∈ bangRel Rel" by(rule Rel.BRBang)
  ultimately show ?thesis by(auto simp add: weakSimulation_def)
qed

lemma bangRelSim:
  fixes P    :: pi
  and   Q    :: pi
  and   Rel  :: "(pi × pi) set"
  and   Rel'l :: "(pi × pi) set"

  assumes PBangRelQ: "(P, Q) ∈ bangRel Rel"
  and     Sim:       "⋀R S. (R, S) ∈ Rel ⟹ R ↝<Rel> S"

  and     ParComp:     "⋀R S T U. ⟦(R, S) ∈ Rel; (T, U) ∈ Rel'⟧ ⟹ (R ∥ T, S ∥ U) ∈ Rel'"
  and     Res:         "⋀R S x. (R, S) ∈ Rel' ⟹ (<νx>R, <νx>S) ∈ Rel'"

  and     RelStay:        "⋀R S. (R ∥ !R, S) ∈ Rel' ⟹ (!R, S) ∈ Rel'"
  and     BangRelRel': "(bangRel Rel) ⊆ Rel'"
  and     eqvtRel':    "eqvt Rel'"
  and     Eqvt: "eqvt Rel"

  shows "P ↝<Rel'> Q"
proof -
  from PBangRelQ show ?thesis
  proof(induct rule: bangRel.induct)
    case(BRBang P Q)
    have PRelQ: "(P, Q) ∈ Rel" by fact
    thus ?case using ParComp Res BangRelRel' eqvtRel' Eqvt RelStay Sim
      by(rule_tac bangPres)
  next
    case(BRPar P Q R T) 
    have "(P, Q) ∈ Rel" by fact
    moreover hence "P ↝<Rel> Q" by(rule Sim)
    moreover have "R ↝<Rel'> T" by fact
    moreover have "(R, T) ∈ bangRel Rel" by fact
    ultimately show ?case using ParComp eqvtRel' Res Eqvt BangRelRel'
      by(blast intro: parCompose)
  next
    case(BRRes P Q x)
    have "P ↝<Rel'> Q" by fact
    thus ?case using BangRelRel' eqvtRel' Res by(blast intro: resPres)
  qed
qed

end