Theory Differential_Axioms

theory "Differential_Axioms" 
imports
  Ordinary_Differential_Equations.ODE_Analysis
  "Ids"
  "Lib"
  "Syntax"     
  "Denotational_Semantics"
  "Frechet_Correctness"
  "Axioms"
  "Coincidence"
begin context ids begin
section ‹Differential Axioms›
text ‹Differential axioms fall into two categories:
Axioms for computing the derivatives of terms and axioms for proving properties of ODEs.
The derivative axioms are all corollaries of the frechet correctness theorem. The ODE
axioms are more involved, often requiring extensive use of the ODE libraries.› 

subsection ‹Derivative Axioms›
definition diff_const_axiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"diff_const_axiom ≡ Equals (Differential ($f fid1 empty)) (Const 0)"

definition diff_var_axiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"diff_var_axiom ≡ Equals (Differential (Var vid1)) (DiffVar vid1)"
  
definition state_fun ::"'sf ⇒ ('sf, 'sz) trm"
where [axiom_defs]:"state_fun f = ($f f (λi. Var i))"
  
definition diff_plus_axiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"diff_plus_axiom ≡ Equals (Differential (Plus (state_fun fid1) (state_fun fid2))) 
    (Plus (Differential (state_fun fid1)) (Differential (state_fun fid2)))"

definition diff_times_axiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"diff_times_axiom ≡ Equals (Differential (Times (state_fun fid1) (state_fun fid2))) 
    (Plus (Times (Differential (state_fun fid1)) (state_fun fid2)) 
          (Times (state_fun fid1) (Differential (state_fun fid2))))"

― ‹‹[y=g(x)][y'=1](f(g(x))' = f(y)')››
definition diff_chain_axiom::"('sf, 'sc, 'sz) formula"
where [axiom_defs]:"diff_chain_axiom ≡ [[Assign vid2 (f1 fid2 vid1)]]([[DiffAssign vid2 (Const 1)]] 
  (Equals (Differential ($f fid1 (singleton (f1 fid2 vid1)))) (Times (Differential (f1 fid1 vid2)) (Differential (f1 fid2 vid1)))))"

subsection ‹ODE Axioms›
definition DWaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DWaxiom = ([[EvolveODE (OVar vid1) (Predicational pid1)]](Predicational pid1))"

definition DWaxiom' :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DWaxiom' = ([[EvolveODE (OSing vid1 (Function fid1 (singleton (Var vid1)))) (Prop vid2 (singleton (Var vid1)))]](Prop vid2 (singleton (Var vid1))))"
  
definition DCaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DCaxiom = (
([[EvolveODE (OVar vid1) (Predicational pid1)]]Predicational pid3) →
(([[EvolveODE (OVar vid1) (Predicational pid1)]](Predicational pid2)) 
  ↔  
   ([[EvolveODE (OVar vid1) (And (Predicational pid1) (Predicational pid3))]]Predicational pid2)))"

definition DEaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DEaxiom = 
(([[EvolveODE (OSing vid1 (f1 fid1 vid1)) (p1 vid2 vid1)]] (P pid1))
↔
 ([[EvolveODE (OSing vid1 (f1 fid1 vid1)) (p1 vid2 vid1)]]
    [[DiffAssign vid1 (f1 fid1 vid1)]]P pid1))"
  
definition DSaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DSaxiom = 
(([[EvolveODE (OSing vid1 (f0 fid1)) (p1 vid2 vid1)]]p1 vid3 vid1)
↔ 
(Forall vid2 
 (Implies (Geq (Var vid2) (Const 0)) 
 (Implies 
   (Forall vid3 
     (Implies (And (Geq (Var vid3) (Const 0)) (Geq (Var vid2) (Var vid3)))
        (Prop vid2 (singleton (Plus (Var vid1) (Times (f0 fid1) (Var vid3)))))))
   ([[Assign vid1 (Plus (Var vid1) (Times (f0 fid1) (Var vid2)))]]p1 vid3 vid1)))))"

― ‹‹(Q → [c&Q](f(x)' ≥ g(x)'))›› 
― ‹‹→››
― ‹‹([c&Q](f(x) ≥ g(x))) --> (Q → (f(x) ≥ g(x))›› 
definition DIGeqaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DIGeqaxiom = 
Implies 
  (Implies (Prop vid1 empty) ([[EvolveODE (OVar vid1) (Prop vid1 empty)]](Geq (Differential (f1 fid1 vid1)) (Differential (f1 fid2 vid1)))))
  (Implies
     (Implies(Prop vid1 empty) (Geq (f1 fid1 vid1) (f1 fid2 vid1)))
     ([[EvolveODE (OVar vid1) (Prop vid1 empty)]](Geq (f1 fid1 vid1) (f1 fid2 vid1))))"


― ‹‹g(x) > h(x) → [x'=f(x), c & p(x)](g(x)' ≥ h(x)') → [x'=f(x), c & p(x)]g(x) > h(x)›› 

― ‹‹(Q → [c&Q](f(x)' ≥ g(x)'))›› 
― ‹‹→››
― ‹‹([c&Q](f(x) > g(x))) <-> (Q → (f(x) > g(x))››
definition DIGraxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DIGraxiom = 
Implies 
  (Implies (Prop vid1 empty) ([[EvolveODE (OVar vid1) (Prop vid1 empty)]](Geq (Differential (f1 fid1 vid1)) (Differential (f1 fid2 vid1)))))
  (Implies
     (Implies(Prop vid1 empty) (Greater (f1 fid1 vid1) (f1 fid2 vid1)))
     ([[EvolveODE (OVar vid1) (Prop vid1 empty)]](Greater (f1 fid1 vid1) (f1 fid2 vid1))))"

― ‹‹[{1' = 1(1) & 1(1)}]2(1) <->››
― ‹‹∃2. [{1'=1(1), 2' = 2(1)*2 + 3(1) & 1(1)}]2(1)*)››
definition DGaxiom :: "('sf, 'sc, 'sz) formula"
where [axiom_defs]:"DGaxiom = (([[EvolveODE (OSing vid1 (f1 fid1 vid1)) (p1 vid1 vid1)]]p1 vid2 vid1) ↔ 
  (Exists vid2 
    ([[EvolveODE (OProd (OSing vid1 (f1 fid1 vid1)) (OSing vid2 (Plus (Times (f1 fid2 vid1) (Var vid2)) (f1 fid3 vid1)))) (p1 vid1 vid1)]]
       p1 vid2 vid1)))"

subsection ‹Proofs for Derivative Axioms›
lemma constant_deriv_inner:
 assumes interp:"∀x i. (Functions I i has_derivative FunctionFrechet I i x) (at x)"
 shows "FunctionFrechet I id1 (vec_lambda (λi. sterm_sem I (empty i) (fst ν))) (vec_lambda(λi. frechet I (empty i) (fst ν) (snd ν)))= 0"
proof -
  have empty_zero:"(vec_lambda(λi. frechet I (empty i) (fst ν) (snd ν))) = 0"
    using local.empty_def Cart_lambda_cong frechet.simps(5) zero_vec_def
    apply auto
    apply(rule vec_extensionality)
    using local.empty_def Cart_lambda_cong frechet.simps(5) zero_vec_def
    by (simp add: local.empty_def)
  let ?x = "(vec_lambda (λi. sterm_sem I (empty i) (fst ν)))"
  from interp
  have has_deriv:"(Functions I id1 has_derivative FunctionFrechet I id1 ?x) (at ?x)"
    by auto
  then have f_linear:"linear (FunctionFrechet I id1 ?x)"
    using Deriv.has_derivative_linear by auto
  then show ?thesis using empty_zero f_linear linear_0 by (auto)
qed

lemma constant_deriv_zero:"is_interp I ⟹ directional_derivative I ($f id1 empty) ν = 0"
  apply(simp only: is_interp_def directional_derivative_def frechet.simps frechet_correctness)
  apply(rule constant_deriv_inner)
  apply(auto)
done

theorem diff_const_axiom_valid: "valid diff_const_axiom"
  apply(simp only: valid_def diff_const_axiom_def equals_sem)
  apply(rule allI | rule impI)+
  apply(simp only: dterm_sem.simps constant_deriv_zero sterm_sem.simps)
done

theorem diff_var_axiom_valid: "valid diff_var_axiom"
  apply(auto simp add: diff_var_axiom_def valid_def directional_derivative_def)
  by (metis inner_prod_eq)
  
theorem diff_plus_axiom_valid: "valid diff_plus_axiom"
  apply(auto simp add: diff_plus_axiom_def valid_def)
  subgoal for I a b
    using frechet_correctness[of I "(Plus (state_fun fid1) (state_fun fid2))" b] 
    unfolding state_fun_def apply (auto intro: dfree.intros)
    unfolding directional_derivative_def by auto
 done
  
theorem diff_times_axiom_valid: "valid diff_times_axiom"
  apply(auto simp add: diff_times_axiom_def valid_def)
  subgoal for I a b
    using frechet_correctness[of I "(Times (state_fun fid1) (state_fun fid2))" b] 
    unfolding state_fun_def apply (auto intro: dfree.intros)
    unfolding directional_derivative_def by auto
  done
  
subsection ‹Proofs for ODE Axioms›
 
lemma DW_valid:"valid DWaxiom"
  apply(unfold DWaxiom_def valid_def Let_def impl_sem )
  apply(safe)
  apply(auto simp only: fml_sem.simps prog_sem.simps box_sem)
  subgoal for I aa ba ab bb sol t using mk_v_agree[of I "(OVar vid1)" "(ab,bb)" "sol t"]
    Vagree_univ[of "aa" "ba" "sol t" "ODEs I vid1 (sol t)"] solves_ode_domainD
    by (fastforce)
  done

lemma DE_lemma:
  fixes ab bb::"'sz simple_state"
  and sol::"real ⇒ 'sz simple_state"
  and I::"('sf, 'sc, 'sz) interp"
  shows
  "repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1 (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))
   = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)"
proof
  have set_eq:" {Inl vid1, Inr vid1} = {Inr vid1, Inl vid1}" by auto
  have agree:"Vagree (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) (mk_xode I (OSing vid1 (f1 fid1 vid1)) (sol t))
      {Inl vid1, Inr vid1}" 
    using mk_v_agree[of I "(OSing vid1 (f1 fid1 vid1))" "(ab, bb)" "(sol t)"] 
    unfolding semBV.simps using set_eq by auto
  have fact:"dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t))
          = snd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) $ vid1"
    using agree unfolding Vagree_def dterm_sem.simps f1_def mk_xode.simps
  proof -
    assume alls:"(∀i. Inl i ∈ {Inl vid1, Inr vid1} ⟶
        fst (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t)) $ i =
        fst (sol t, ODE_sem I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (sol t)) $ i) ∧
      (∀i. Inr i ∈ {Inl vid1, Inr vid1} ⟶
        snd (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t)) $ i =
        snd (sol t, ODE_sem I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (sol t)) $ i)"
    hence atVid'':"snd (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t)) $ vid1 = sterm_sem I ($f fid1 (singleton (trm.Var vid1))) (sol t)" 
      by auto
    have argsEq:"(χ i. dterm_sem I (singleton (trm.Var vid1) i)
          (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t)))
          = (χ i.  sterm_sem I (singleton (trm.Var vid1) i) (sol t))"
      using alls f1_def by auto
    thus "Functions I fid1 (χ i. dterm_sem I (singleton (trm.Var vid1) i)
          (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t))) 
        = snd (mk_v I (OSing vid1 ($f fid1 (singleton (trm.Var vid1)))) (ab, bb) (sol t)) $ vid1"
      by (simp only: atVid'' ODE_sem.simps sterm_sem.simps dterm_sem.simps)
  qed
  have eqSnd:"(χ y. if vid1 = y then snd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) $ vid1
        else snd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) $ y) = snd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t))"
    by (simp add: vec_extensionality)
  have truth:"repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
        (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))
      = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)"
    using fact by (auto simp only: eqSnd repd.simps fact prod.collapse split: if_split)
  thus "fst (repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
          (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))) =
    fst (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t))"

    "snd (repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
      (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))) =
    snd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) " 
    by auto
qed

lemma DE_valid:"valid DEaxiom"
proof -
  have dsafe:"dsafe ($f fid1 (singleton (trm.Var vid1)))" unfolding singleton_def by(auto intro: dsafe.intros)
  have osafe:"osafe(OSing vid1 (f1 fid1 vid1))" unfolding f1_def empty_def singleton_def using dsafe osafe.intros dsafe.intros
    by (simp add: osafe_Sing dfree_Const) 
  have fsafe:"fsafe (p1 vid2 vid1)" unfolding p1_def singleton_def using hpsafe_fsafe.intros(10)
    using dsafe dsafe_Fun_simps image_iff
    by (simp add: dfree_Const)
  show "valid DEaxiom"
    apply(auto simp only: DEaxiom_def valid_def Let_def iff_sem impl_sem)
     apply(auto simp only: fml_sem.simps prog_sem.simps mem_Collect_eq box_sem)
   proof -
     fix I::"('sf,'sc,'sz) interp"
       and aa ba ab bb sol 
       and t::real
       and ac bc
     assume "is_interp I"
     assume allw:"∀ω. (∃ν sol t.
                  ((ab, bb), ω) = (ν, mk_v I (OSing vid1 (f1 fid1 vid1)) ν (sol t)) ∧
                  0 ≤ t ∧
                  (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f1 fid1 vid1)))) {0..t}
                   {x. mk_v I (OSing vid1 (f1 fid1 vid1)) ν x ∈ fml_sem I (p1 vid2 vid1)} ∧
                  (sol 0) = (fst ν) ) ⟶
              ω ∈ fml_sem I (P pid1)"
     assume t:"0 ≤ t"
     assume aaba:"(aa, ba) = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)"
     assume solve:" (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f1 fid1 vid1)))) {0..t}
         {x. mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"
     assume sol0:" (sol 0) = (fst (ab, bb)) "
     assume rep:"   (ac, bc) =
        repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
         (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))"
     have aaba_sem:"(aa,ba) ∈ fml_sem I (P pid1)" using allw t aaba solve sol0 rep by blast
     have truth:"repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
          (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))
     = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)"
       using DE_lemma by auto
     show "
        repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1
         (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))
        ∈ fml_sem I (P pid1)" using aaba aaba_sem truth by (auto)
   next
     fix I::"('sf,'sc,'sz) interp" and  aa ba ab bb sol and t::real
       assume "is_interp I"
       assume all:"∀ω. (∃ν sol t.
                ((ab, bb), ω) = (ν, mk_v I (OSing vid1 (f1 fid1 vid1)) ν (sol t)) ∧
                0 ≤ t ∧
                (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f1 fid1 vid1)))) {0..t}
                 {x. mk_v I (OSing vid1 (f1 fid1 vid1)) ν x ∈ fml_sem I (p1 vid2 vid1)} ∧
                 (sol 0) = (fst ν) ) ⟶
            (∀ω'. ω' = repd ω vid1 (dterm_sem I (f1 fid1 vid1) ω) ⟶ ω' ∈ fml_sem I (P pid1))"
       hence justW:"(∃ν sol t.
                ((ab, bb), (aa, ba)) = (ν, mk_v I (OSing vid1 (f1 fid1 vid1)) ν (sol t)) ∧
                0 ≤ t ∧
                (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f1 fid1 vid1)))) {0..t}
                 {x. mk_v I (OSing vid1 (f1 fid1 vid1)) ν x ∈ fml_sem I (p1 vid2 vid1)} ∧
                (sol 0) = (fst ν)) ⟶
            (∀ω'. ω' = repd (aa, ba) vid1 (dterm_sem I (f1 fid1 vid1) (aa, ba)) ⟶ ω' ∈ fml_sem I (P pid1))"
         by (rule allE)
       assume t:"0 ≤ t"
       assume aaba:"(aa, ba) = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)"
       assume sol:"(sol solves_ode (λ_. ODE_sem I (OSing vid1 (f1 fid1 vid1)))) {0..t}
        {x. mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"
       assume sol0:" (sol 0) = (fst (ab, bb))"
       have "repd (aa, ba) vid1 (dterm_sem I (f1 fid1 vid1) (aa, ba)) ∈ fml_sem I (P pid1)"
         using justW t aaba sol sol0 by auto
       hence foo:"repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1 (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t))) ∈ fml_sem I (P pid1)"
         using aaba by auto
       hence "repd (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)) vid1 (dterm_sem I (f1 fid1 vid1) (mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)))
             = mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t)" using DE_lemma by auto
       thus "mk_v I (OSing vid1 (f1 fid1 vid1)) (ab, bb) (sol t) ∈ fml_sem I (P pid1)" using foo by auto
  qed
qed

lemma ODE_zero:"⋀i. Inl i ∉ BVO ODE ⟹ Inr i ∉ BVO ODE ⟹ ODE_sem I ODE ν $ i= 0"
  by(induction ODE, auto)

lemma DE_sys_valid:
  assumes disj:"{Inl vid1, Inr vid1} ∩ BVO ODE = {}"
  shows "valid (([[EvolveODE (OProd  (OSing vid1 (f1 fid1 vid1)) ODE) (p1 vid2 vid1)]] (P pid1)) ↔
 ([[EvolveODE ((OProd  (OSing vid1 (f1 fid1 vid1))ODE)) (p1 vid2 vid1)]]
    [[DiffAssign vid1 (f1 fid1 vid1)]]P pid1))"
proof -
  have dsafe:"dsafe ($f fid1 (singleton (trm.Var vid1)))" unfolding singleton_def by(auto intro: dsafe.intros)
  have osafe:"osafe(OSing vid1 (f1 fid1 vid1))" unfolding f1_def empty_def singleton_def using dsafe osafe.intros dsafe.intros
    by (simp add: osafe_Sing dfree_Const) 
  have fsafe:"fsafe (p1 vid2 vid1)" unfolding p1_def singleton_def using hpsafe_fsafe.intros(10)
    using dsafe dsafe_Fun_simps image_iff
    by (simp add: dfree_Const)
  show "valid (([[EvolveODE (OProd (OSing vid1 (f1 fid1 vid1)) ODE) (p1 vid2 vid1)]] (P pid1)) ↔
 ([[EvolveODE ((OProd (OSing vid1 (f1 fid1 vid1)) ODE)) (p1 vid2 vid1)]]
    [[DiffAssign vid1 (f1 fid1 vid1)]]P pid1))"
    apply(auto simp only: DEaxiom_def valid_def Let_def iff_sem impl_sem)
    apply(auto simp only: fml_sem.simps prog_sem.simps mem_Collect_eq box_sem f1_def p1_def P_def expand_singleton)
   proof -
     fix I ::"('sf,'sc,'sz) interp"
       and aa ba ab bb sol 
       and t::real
       and ac bc
     assume good:"is_interp I"
     assume bigAll:"
     ∀ω. (∃ν sol t. ((ab, bb), ω) = (ν, mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) ODE) ν (sol t)) ∧
                    0 ≤ t ∧
                    (sol solves_ode (λ_. ODE_sem I (OProd(OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) ODE ))) {0..t}
                     {x. Predicates I vid2
                          (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                 (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν x))} ∧
                    sol 0 = fst ν) ⟶
          ω ∈ fml_sem I (Pc pid1)"
     let ?myω = "mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab,bb) (sol t)"
     assume t:"0 ≤ t"
     assume aaba:"(aa, ba) = mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)"
     assume sol:"(sol solves_ode (λ_. ODE_sem I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE))) {0..t}
      {x. Predicates I vid2
           (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                  (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) x))}"
     assume sol0:"sol 0 = fst (ab, bb)"
     assume acbc:"(ac, bc) =
     repd (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)) vid1
      (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))
        (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)))"
     have bigEx:"(∃ν sol t. ((ab, bb), ?myω) = (ν, mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν (sol t)) ∧
                    0 ≤ t ∧
                    (sol solves_ode (λ_. ODE_sem I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE))) {0..t}
                     {x. Predicates I vid2
                          (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                 (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν x))} ∧
                    sol 0 = fst ν)"
       apply(rule exI[where x="(ab, bb)"])
       apply(rule exI[where x="sol"])
       apply(rule exI[where x="t"])
       apply(rule conjI) 
        apply(rule refl)
       apply(rule conjI)
        apply(rule t)
       apply(rule conjI)
        using sol apply blast
       by (rule sol0)
     have bigRes:"?myω ∈ fml_sem I (Pc pid1)" using bigAll bigEx by blast
     have notin1:"Inl vid1 ∉ BVO ODE" using disj by auto
     have notin2:"Inr vid1 ∉ BVO ODE" using disj by auto
     have ODE_sem:"ODE_sem I ODE (sol t) $ vid1 = 0"
       using ODE_zero notin1 notin2 
       by blast 
     have vec_eq:"(χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (sol t)) =
           (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
            (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)))"
       apply(rule vec_extensionality)
       apply simp
       using mk_v_agree[of I "(OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE)" "(ab, bb)" "(sol t)"]
       by(simp add: Vagree_def)
     have sem_eq:"(?myω ∈ fml_sem I (Pc pid1)) = ((repd (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)) vid1
     (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))
       (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)))) ∈ fml_sem I (Pc pid1))"
       apply(rule coincidence_formula)
         subgoal by simp
        subgoal by (rule Iagree_refl)
       using mk_v_agree[of "I" "(OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE)" "(ab, bb)" "(sol t)"]
       unfolding Vagree_def 
       apply simp
       apply(erule conjE)+
       apply(erule allE[where x="vid1"])+
       apply(simp add: ODE_sem)
       using vec_eq by simp
     show  "repd (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)) vid1
      (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))
        (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)))
     ∈ fml_sem I (Pc pid1)"
       using bigRes sem_eq by blast
   next
     fix I::"('sf,'sc,'sz)interp" 
     and aa ba ab bb sol 
     and t::real
     assume good_interp:"is_interp I"
     assume all:"∀ω. (∃ν sol t. ((ab, bb), ω) = (ν, mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν (sol t)) ∧
                       0 ≤ t ∧
                       (sol solves_ode (λ_. ODE_sem I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE))) {0..t}
                        {x. Predicates I vid2
                             (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                    (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν x))} ∧
                       sol 0 = fst ν) ⟶
             (∀ω'. ω' = repd ω vid1 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ω) ⟶ ω' ∈ fml_sem I (Pc pid1))"
      let ?myω = "mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)" 
      assume t:"0 ≤ t"
      assume aaba:"(aa, ba) = mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)"
      assume sol:"
        (sol solves_ode (λ_. ODE_sem I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE))) {0..t}
         {x. Predicates I vid2
              (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                    (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) x))}"
      assume sol0:"sol 0 = fst (ab, bb)"
      have bigEx:"(∃ν sol t. ((ab, bb), ?myω) = (ν, mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν (sol t)) ∧
                      0 ≤ t ∧
                      (sol solves_ode (λ_. ODE_sem I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE))) {0..t}
                       {x. Predicates I vid2
                            (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                   (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) ν x))} ∧
                      sol 0 = fst ν)"
        apply(rule exI[where x="(ab, bb)"])
        apply(rule exI[where x=sol])
        apply(rule exI[where x=t])
        apply(rule conjI)
         apply(rule refl)
        apply(rule conjI)
         apply(rule t)
        apply(rule conjI)
         using sol sol0 by(blast)+
      have rep_sem_eq:"repd (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)) vid1
                 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))
                   (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)))  ∈ fml_sem I (Pc pid1)
         = (repd ?myω vid1 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ?myω) ∈ fml_sem I (Pc pid1))"
        apply(rule coincidence_formula)
          subgoal by simp
         subgoal by (rule Iagree_refl)
        by(simp add: Vagree_def)
      have notin1:"Inl vid1 ∉ BVO ODE" using disj by auto
      have notin2:"Inr vid1 ∉ BVO ODE" using disj by auto
      have ODE_sem:"ODE_sem I ODE (sol t) $ vid1 = 0"
        using ODE_zero notin1 notin2 
        by blast 
      have vec_eq:"
      (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
             (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t))) =
      (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (sol t))"
        apply(rule vec_extensionality)
        using mk_v_agree[of I "(OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE)" "(ab, bb)" "(sol t)"]
        by (simp add: Vagree_def)
      have sem_eq:
        "(repd ?myω vid1 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ?myω) ∈ fml_sem I (Pc pid1)) 
     = (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t) ∈ fml_sem I (Pc pid1)) "
        apply(rule coincidence_formula)
          subgoal by simp
         subgoal by (rule Iagree_refl)
        using mk_v_agree[of I "(OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE)" "(ab, bb)" "(sol t)"]
        unfolding Vagree_def apply simp
        apply(erule conjE)+
        apply(erule allE[where x=vid1])+
        by (simp add: ODE_sem vec_eq)
      have some_sem:"repd (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t)) vid1
                (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))
                  (mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t))) ∈ fml_sem I (Pc pid1)"
        using rep_sem_eq 
        using all bigEx by blast
      have bigImp:"(∀ω'. ω' = repd ?myω vid1 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ?myω) ⟶ ω' ∈ fml_sem I (Pc pid1))"
        apply(rule allI)
        apply(rule impI)
        apply auto
        using some_sem by auto
      have fml_sem:"repd ?myω vid1 (dterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ?myω) ∈ fml_sem I (Pc pid1)"
        using sem_eq bigImp by blast
     show "mk_v I (OProd  (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))ODE) (ab, bb) (sol t) ∈ fml_sem I (Pc pid1)"
       using fml_sem sem_eq by blast
   qed
qed

lemma DC_valid:"valid DCaxiom" 
proof (auto simp only: fml_sem.simps prog_sem.simps DCaxiom_def valid_def iff_sem impl_sem box_sem, auto)
  fix I::"('sf,'sc,'sz) interp" and aa ba bb sol t
  assume "is_interp I"
    and all3:"∀a b. (∃sola. sol 0 = sola 0 ∧
                  (∃t. (a, b) = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                        0 ≤ t ∧ (sola solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV})) ⟶
           (a, b) ∈ Contexts I pid3 UNIV"
    and all2:"∀a b. (∃sola. sol 0 = sola 0 ∧
                   (∃t. (a, b) = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                        0 ≤ t ∧ (sola solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV})) ⟶
           (a, b) ∈ Contexts I pid2 UNIV"
    and t:"0 ≤ t"
    and aaba:"(aa, ba) = mk_v I (OVar vid1) (sol 0, bb) (sol t)"
    and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
       {x. mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid1 UNIV ∧ mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid3 UNIV}"
    from sol have
          sol1:"(sol solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid1 UNIV}"
      by (metis (mono_tags, lifting) Collect_mono solves_ode_supset_range)
    from all2 have all2':"⋀v. (∃sola. sol 0 = sola 0 ∧
                   (∃t. v = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                        0 ≤ t ∧ (sola solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV})) ⟹
           v ∈ Contexts I pid2 UNIV" by auto
    show "mk_v I (OVar vid1) (sol 0, bb) (sol t) ∈ Contexts I pid2 UNIV" 
      apply(rule all2'[of "mk_v I (OVar vid1) (sol 0, bb) (sol t)"])
      apply(rule exI[where x=sol])
      apply(rule conjI)
       subgoal by (rule refl)
      subgoal using t sol1 by auto
     done
next
  fix I::"('sf,'sc,'sz) interp" and  aa ba bb sol t
  assume "is_interp I"
  and all3:"∀a b. (∃sola. sol 0 = sola 0 ∧
                (∃t. (a, b) = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                     0 ≤ t ∧ (sola solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV})) ⟶
        (a, b) ∈ Contexts I pid3 UNIV"
  and all2:"∀a b. (∃sola. sol 0 = sola 0 ∧
                (∃t. (a, b) = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                     0 ≤ t ∧
                     (sola solves_ode (λa. ODEs I vid1)) {0..t}
                       {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV ∧
                          mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid3 UNIV})) ⟶
        (a, b) ∈ Contexts I pid2 UNIV"
  and t:"0 ≤ t"
  and aaba:"(aa, ba) = mk_v I (OVar vid1) (sol 0, bb) (sol t)"
  and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid1 UNIV}"
  from all2 
  have all2':"⋀v. (∃sola. sol 0 = sola 0 ∧
                (∃t. v = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                     0 ≤ t ∧
                     (sola solves_ode (λa. ODEs I vid1)) {0..t}
                      {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV ∧
                          mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid3 UNIV})) ⟹
        v ∈ Contexts I pid2 UNIV"
    by auto
  from all3
  have all3':"⋀v. (∃sola. sol 0 = sola 0 ∧
                (∃t. v = mk_v I (OVar vid1) (sola 0, bb) (sola t) ∧
                     0 ≤ t ∧ (sola solves_ode (λa. ODEs I vid1)) {0..t} {x. mk_v I (OVar vid1) (sola 0, bb) x ∈ Contexts I pid1 UNIV})) ⟹
        v ∈ Contexts I pid3 UNIV"
    by auto
  have inp1:"⋀s. 0 ≤ s ⟹ s ≤ t ⟹ mk_v I (OVar vid1) (sol 0, bb) (sol s) ∈ Contexts I pid1 UNIV"
    using sol solves_odeD atLeastAtMost_iff by blast
  have inp3:"⋀s. 0 ≤ s ⟹ s ≤ t ⟹ mk_v I (OVar vid1) (sol 0, bb) (sol s) ∈ Contexts I pid3 UNIV"
    apply(rule all3')
    subgoal for s 
      apply(rule exI [where x=sol])
      apply(rule conjI)
       subgoal by (rule refl)
      apply(rule exI [where x=s])
      apply(rule conjI)
       subgoal by (rule refl)
      apply(rule conjI)
       subgoal by assumption
      subgoal using sol by (meson atLeastatMost_subset_iff order_refl solves_ode_subset)
      done
   done
   have inp13:"⋀s. 0 ≤ s ⟹ s ≤ t ⟹ mk_v I (OVar vid1) (sol 0, bb) (sol s) ∈ Contexts I pid1 UNIV ∧ mk_v I (OVar vid1) (sol 0, bb) (sol s) ∈ Contexts I pid3 UNIV"
     using inp1 inp3 by auto
   have sol13:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
     {x. mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid1 UNIV ∧ mk_v I (OVar vid1) (sol 0, bb) x ∈ Contexts I pid3 UNIV}"
     apply(rule solves_odeI)
      subgoal using sol by (rule solves_odeD)
     subgoal for s using inp13[of s] by auto
     done
  show "mk_v I (OVar vid1) (sol 0, bb) (sol t) ∈ Contexts I pid2 UNIV"
    using t sol13 all2'[of "mk_v I (OVar vid1) (sol 0, bb) (sol t)"] by auto
qed

lemma DS_valid:"valid DSaxiom"
proof -
  have dsafe:"dsafe($f fid1 (λi. Const 0))"
    using dsafe_Const by auto
  have osafe:"osafe(OSing vid1 (f0 fid1))"
    unfolding f0_def empty_def
    using dsafe osafe.intros
    by (simp add: osafe_Sing dfree_Const)
  have fsafe:"fsafe(p1 vid2 vid1)"
    unfolding p1_def
    apply(rule fsafe_Prop)
    using singleton.simps dsafe_Const by (auto intro: dfree.intros)
  show "valid DSaxiom"
    apply(auto simp only: DSaxiom_def valid_def Let_def iff_sem impl_sem box_sem)
     apply(auto simp only: fml_sem.simps prog_sem.simps mem_Collect_eq  iff_sem impl_sem box_sem forall_sem)
  proof -
    fix I::"('sf,'sc,'sz) interp" 
      and a b r aa ba
    assume good_interp:"is_interp I"
    assume allW:"∀ω. (∃ν sol t.
             ((a, b), ω) = (ν, mk_v I (OSing vid1 (f0 fid1)) ν (sol t)) ∧
             0 ≤ t ∧
             (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..t}
              {x. mk_v I (OSing vid1 (f0 fid1)) ν x ∈ fml_sem I (p1 vid2 vid1)} ∧
              (sol 0) = (fst ν)) ⟶
         ω ∈ fml_sem I (p1 vid3 vid1)"
    assume "dterm_sem I (Const 0) (repv (a, b) vid2 r) ≤ dterm_sem I (trm.Var vid2) (repv (a, b) vid2 r)"
    hence leq:"0 ≤ r" by (auto)
    assume "∀ra. repv (repv (a, b) vid2 r) vid3 ra
         ∈ {v. dterm_sem I (Const 0) v ≤ dterm_sem I (trm.Var vid3) v} ∩
            {v. dterm_sem I (trm.Var vid3) v ≤ dterm_sem I (trm.Var vid2) v} ⟶
         Predicates I vid2
          (χ i. dterm_sem I (singleton (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3))) i)
                 (repv (repv (a, b) vid2 r) vid3 ra))"
    hence constraint:"∀ra. (0 ≤ ra ∧ ra ≤ r) ⟶ 
         (repv (repv (a, b) vid2 r) vid3 ra) 
       ∈ fml_sem I (Prop vid2 (singleton (Plus (Var vid1) (Times (f0 fid1) (Var vid3)))))"
      using leq by auto
    assume aaba:" (aa, ba) =
     repv (repv (a, b) vid2 r) vid1
      (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (a, b) vid2 r))"
    let ?abba = "repv (repd (a, b) vid1 (Functions I fid1 (χ i. 0))) vid1
      (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (a, b) vid2 r))"
    from allW have thisW:"(∃ν sol t.
            ((a, b), ?abba) = (ν, mk_v I (OSing vid1 (f0 fid1)) ν (sol t)) ∧
            0 ≤ t ∧
            (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..t}
             {x. mk_v I (OSing vid1 (f0 fid1)) ν x ∈ fml_sem I (p1 vid2 vid1)} ∧
             (sol 0) = (fst ν)) ⟶
        ?abba ∈ fml_sem I (p1 vid3 vid1)" by blast
    let ?c = "Functions I fid1 (χ _. 0)"
    let ?sol = "(λt. χ i. if i = vid1 then (a $ i) + ?c * t else (a $ i))"
    have agrees:"Vagree (mk_v I (OSing vid1 (f0 fid1)) (a, b) (?sol r)) (a, b) (- semBV I (OSing vid1 (f0 fid1))) 
  ∧ Vagree (mk_v I (OSing vid1 (f0 fid1)) (a, b) (?sol r))
   (mk_xode I (OSing vid1 (f0 fid1)) (?sol r)) (semBV I (OSing vid1 (f0 fid1)))" 
       using mk_v_agree[of "I" "(OSing vid1 (f0 fid1))" "(a,b)" "(?sol r)"] by auto
    have prereq1a:"fst ?abba
     = fst (mk_v I (OSing vid1 (f0 fid1)) (a,b) (?sol r))"
      using  agrees aaba 
      apply (auto simp add: aaba Vagree_def)
       apply (rule vec_extensionality)
       subgoal for i
         apply (cases "i = vid1")
          using vne12 agrees Vagree_def apply (auto simp add: aaba f0_def empty_def)
         done
      apply (rule vec_extensionality)
      subgoal for i
        apply (cases "i = vid1")
         apply(auto  simp add: f0_def empty_def)
      done
    done
  have prereq1b:"snd (?abba) = snd (mk_v I (OSing vid1 (f0 fid1)) (a,b) (?sol r))"
    using agrees aaba 
    apply (auto simp add: aaba Vagree_def)
    apply (rule vec_extensionality)
    subgoal for i
      apply (cases "i = vid1")
       using vne12 agrees Vagree_def apply (auto simp add: aaba f0_def empty_def )
      done
    done  
  have "?abba = mk_v I (OSing vid1 (f0 fid1)) (a,b) (?sol r)"
    using prod_eq_iff prereq1a prereq1b by blast
  hence req1:"((a, b), ?abba) = ((a, b), mk_v I (OSing vid1 (f0 fid1)) (a,b) (?sol r))" by auto
  have "sterm_sem I ($f fid1 (λi. Const 0)) b = Functions I fid1 (χ i. 0)" by auto
  hence vec_simp:"(λa b. χ i. if i = vid1 then sterm_sem I ($f fid1 (λi. Const 0)) b else 0) 
      = (λa b. χ i. if i = vid1 then Functions I fid1 (χ i. 0) else 0)"
    by (auto simp add: vec_eq_iff cong: if_cong)
  have sub: "{0..r} ⊆ UNIV" by auto
  have sub2:"{x. mk_v I (OSing vid1 (f0 fid1)) (a,b) x ∈ fml_sem I (p1 vid2 vid1)} ⊆ UNIV" by auto
  have req3:"(?sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..r}
            {x. mk_v I (OSing vid1 (f0 fid1)) (a,b) x ∈ fml_sem I (p1 vid2 vid1)}" 
    apply(auto simp add: f0_def empty_def vec_simp) 
    apply(rule solves_odeI)
     apply(auto simp only: has_vderiv_on_def has_vector_derivative_def box_sem)
     apply (rule has_derivative_vec[THEN has_derivative_eq_rhs])
      defer
      apply (rule ext)
      apply (subst scaleR_vec_def)
      apply (rule refl)
     apply (auto intro!: derivative_eq_intros)
    ― ‹Domain constraint satisfied›
    using constraint apply (auto)
    subgoal for t
      apply(erule allE[where x="t"])
      apply(auto simp add: p1_def)
    proof -
      have eq:"(χ i. dterm_sem I (if i = vid1 then Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3)) else Const 0)
            (χ y. if vid3 = y then t else fst (χ y. if vid2 = y then r else fst (a, b) $ y, b) $ y, b)) =
            (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
              (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (a, b)
                (χ i. if i = vid1 then a $ i + Functions I fid1 (χ _. 0) * t else a $ i)))"
        using vne12 vne13 mk_v_agree[of "I" "(OSing vid1 ($f fid1 (λi. Const 0)))" "(a, b)" "(χ i. if i = vid1 then a $ i + Functions I fid1 (χ _. 0) * t else a $ i)"]
        by (auto simp add: vec_eq_iff f0_def empty_def Vagree_def)
      show "0 ≤ t ⟹
    t ≤ r ⟹
    Predicates I vid2
     (χ i. dterm_sem I (if i = vid1 then Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3)) else Const 0)
            (χ y. if vid3 = y then t else fst (χ y. if vid2 = y then r else fst (a, b) $ y, b) $ y, b)) ⟹
    Predicates I vid2
     (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
            (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (a, b)
              (χ i. if i = vid1 then a $ i + Functions I fid1 (χ _. 0) * t else a $ i)))" 
        using eq by auto
    qed
    done
  have req4':"?sol 0 = fst (a,b)" by (auto simp: vec_eq_iff)
  then have req4: " (?sol 0) = (fst (a,b))"
    using VSagree_refl[of a] req4' unfolding VSagree_def by auto
  have inPred:"?abba ∈ fml_sem I (p1 vid3 vid1)"  
    using req1 leq req3 req4 thisW by fastforce
  have sem_eq:"?abba ∈ fml_sem I (p1 vid3 vid1) ⟷ (aa,ba) ∈ fml_sem I (p1 vid3 vid1)"
    apply (rule coincidence_formula)
      apply (auto simp add: aaba Vagree_def p1_def f0_def empty_def)
    subgoal using Iagree_refl by auto
    done
  from inPred sem_eq have  inPred':"(aa,ba) ∈ fml_sem I (p1 vid3 vid1)"
    by auto
  ― ‹thus by lemma 6 consequence for formulas›
  show "repv (repv (a, b) vid2 r) vid1
       (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (a, b) vid2 r))
       ∈ fml_sem I (p1 vid3 vid1)" 
    using aaba inPred' by (auto)
next
  fix I::"('sf,'sc,'sz) interp"
  and aa ba ab bb sol 
  and t:: real
  assume good_interp:"is_interp I"
  assume all:"
       ∀r. dterm_sem I (Const 0) (repv (ab, bb) vid2 r) ≤ dterm_sem I (trm.Var vid2) (repv (ab, bb) vid2 r) ⟶
           (∀ra. repv (repv (ab, bb) vid2 r) vid3 ra
                 ∈ {v. dterm_sem I (Const 0) v ≤ dterm_sem I (trm.Var vid3) v} ∩
                    {v. dterm_sem I (trm.Var vid3) v ≤ dterm_sem I (trm.Var vid2) v} ⟶
                 Predicates I vid2
                  (χ i. dterm_sem I (singleton (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3))) i)
                         (repv (repv (ab, bb) vid2 r) vid3 ra))) ⟶
                         
           (∀ω. ω = repv (repv (ab, bb) vid2 r) vid1
                      (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (ab, bb) vid2 r)) ⟶
                 ω ∈ fml_sem I (p1 vid3 vid1))"
  assume t:"0 ≤ t"
  assume aaba:"(aa, ba) = mk_v I (OSing vid1 (f0 fid1)) (ab, bb) (sol t)"
  assume sol:"(sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..t}
        {x. mk_v I (OSing vid1 (f0 fid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"
  hence constraint:"⋀s. s ∈ {0 .. t} ⟹ sol s ∈ {x. mk_v I (OSing vid1 (f0 fid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"
    using solves_ode_domainD by fastforce
  ― ‹‹sol 0 = fst (ab, bb)››
  assume sol0:"  (sol 0) = (fst (ab, bb)) "
  have impl:"dterm_sem I (Const 0) (repv (ab, bb) vid2 t) ≤ dterm_sem I (trm.Var vid2) (repv (ab, bb) vid2 t) ⟶
           (∀ra. repv (repv (ab, bb) vid2 t) vid3 ra
                 ∈ {v. dterm_sem I (Const 0) v ≤ dterm_sem I (trm.Var vid3) v} ∩
                    {v. dterm_sem I (trm.Var vid3) v ≤ dterm_sem I (trm.Var vid2) v} ⟶
                 Predicates I vid2
                  (χ i. dterm_sem I (singleton (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3))) i)
                         (repv (repv (ab, bb) vid2 t) vid3 ra))) ⟶
           (∀ω. ω = repv (repv (ab, bb) vid2 t) vid1
                      (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (ab, bb) vid2 t)) ⟶
                 ω ∈ fml_sem I (p1 vid3 vid1))" using all by auto
  interpret ll:ll_on_open_it UNIV "(λ_. ODE_sem I (OSing vid1 (f0 fid1)))" "UNIV" 0
    apply(standard)
        apply(auto)
     unfolding local_lipschitz_def f0_def empty_def sterm_sem.simps 
     using gt_ex lipschitz_on_constant by blast
  have eq_UNIV:"ll.existence_ivl 0 (sol 0) = UNIV"
    apply(rule ll.existence_ivl_eq_domain)
        apply(auto)
    subgoal for tm tM t
      apply(unfold f0_def empty_def sterm_sem.simps)
      by(metis add.right_neutral mult_zero_left order_refl)
    done
  ― ‹Combine with ‹flow_usolves_ode› and ‹equals_flowI› to get uniqueness of solution›
  let ?f = "(λ_. ODE_sem I (OSing vid1 (f0 fid1)))"
  have sol_UNIV: "⋀t x. (ll.flow 0 x usolves_ode ?f from 0) (ll.existence_ivl 0 x) UNIV"
    using ll.flow_usolves_ode by auto    
  from sol have sol':
    "(sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..t} UNIV"
    apply (rule solves_ode_supset_range)
    by auto
  from sol' have sol'':"⋀s. s ≥ 0 ⟹ s ≤ t ⟹ (sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..s} UNIV"
    by (simp add: solves_ode_subset)
  have sol0_eq:"sol 0 = ll.flow  0 (sol 0) 0"
    using ll.general.flow_initial_time_if by auto
  have isFlow:"⋀s. s ≥ 0 ⟹ s ≤ t ⟹ sol s = ll.flow 0 (sol 0) s"
    apply(rule ll.equals_flowI)
         apply(auto)
      subgoal using eq_UNIV by auto
     subgoal using sol'' closed_segment_eq_real_ivl t by (auto simp add: solves_ode_singleton)
    subgoal using eq_UNIV sol sol0_eq by auto
    done
  let ?c = "Functions I fid1 (χ _. 0)"
  let ?sol = "(λt. χ i. if i = vid1 then (ab $ i) + ?c * t else (ab $ i))"
  have vec_simp:"(λa b. χ i. if i = vid1 then sterm_sem I ($f fid1 (λi. Const 0)) b else 0) 
      = (λa b. χ i. if i = vid1 then Functions I fid1 (χ i. 0) else 0)"
    by (auto simp add: vec_eq_iff cong: if_cong)
  have exp_sol:"(?sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..t}
    UNIV"
    apply(auto simp add: f0_def empty_def vec_simp) 
    apply(rule solves_odeI)
     apply(auto simp only: has_vderiv_on_def has_vector_derivative_def box_sem)
    apply (rule has_derivative_vec[THEN has_derivative_eq_rhs])
     defer
     apply (rule ext)
     apply (subst scaleR_vec_def)
     apply (rule refl)
    apply (auto intro!: derivative_eq_intros)
    done
  from exp_sol have exp_sol':"⋀s. s ≥ 0 ⟹ s ≤ t ⟹ (?sol solves_ode (λ_. ODE_sem I (OSing vid1 (f0 fid1)))) {0..s} UNIV"
    by (simp add: solves_ode_subset)
  have exp_sol0_eq:"?sol 0 = ll.flow  0 (?sol 0) 0"
    using ll.general.flow_initial_time_if by auto
  have more_eq:"(χ i. if i = vid1 then ab $ i + Functions I fid1 (χ _. 0) * 0 else ab $ i) = sol 0"
    using sol0 
    apply auto 
    apply(rule vec_extensionality)
    by(auto)
  have exp_isFlow:"⋀s. s ≥ 0 ⟹ s ≤ t ⟹ ?sol s = ll.flow 0 (sol 0) s"
    apply(rule ll.equals_flowI)
         apply(auto)
      subgoal using eq_UNIV by auto
     defer
     subgoal for s 
       using eq_UNIV apply auto
       subgoal using exp_sol exp_sol0_eq more_eq 
         apply(auto)
         done
       done
    using exp_sol' closed_segment_eq_real_ivl t apply(auto)
    by (simp add: solves_ode_singleton)
  have sol_eq_exp:"⋀s. s ≥ 0 ⟹ s ≤ t ⟹ ?sol s = sol s"
    unfolding exp_isFlow isFlow by auto
  then have sol_eq_exp_t:"?sol t = sol t"
    using t by auto
  then have sol_eq_exp_t':"sol t $ vid1 = ?sol t $ vid1" by auto
  then have useful:"?sol t $ vid1 = ab $ vid1 + Functions I fid1 (χ i. 0) * t"
    by auto
  from sol_eq_exp_t' useful have useful':"sol t $ vid1 = ab $ vid1 + Functions I fid1 (χ i. 0) * t"
    by auto
  have sol_int:"((ll.flow 0 (sol 0)) usolves_ode ?f from 0) {0..t} {x. mk_v I (OSing vid1 (f0 fid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"
    apply (rule usolves_ode_subset_range[of "(ll.flow 0 (sol 0))" "?f" "0" "{0..t}" "UNIV" "{x. mk_v I (OSing vid1 (f0 fid1)) (ab, bb) x ∈ fml_sem I (p1 vid2 vid1)}"]) 
      subgoal using eq_UNIV sol_UNIV[of "(sol 0)"] apply (auto)
        apply (rule usolves_ode_subset)
           using t by(auto)
    apply(auto)
    using sol apply(auto  dest!: solves_ode_domainD)
    subgoal for xa using isFlow[of xa] by(auto)
    done
  have thing:"⋀s. 0 ≤ s ⟹ s ≤ t ⟹ fst (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (ab, bb) (?sol s)) $ vid1 = ab $ vid1 + Functions I fid1 (χ i. 0) * s"
    subgoal for s
      using mk_v_agree[of I "(OSing vid1 ($f fid1 (λi. Const 0)))" "(ab, bb)" "(?sol s)"] apply auto
      unfolding Vagree_def by auto
    done
  have thing':"⋀s. 0 ≤ s ⟹ s ≤ t ⟹  fst (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (ab, bb) (sol s)) $ vid1 = ab $ vid1 + Functions I fid1 (χ i. 0) * s"
    subgoal for s using thing[of s] sol_eq_exp[of s] by auto done
  have another_eq:"⋀i s. 0 ≤ s ⟹ s ≤ t ⟹ dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                (mk_v I (OSing vid1 (f0 fid1)) (ab, bb) (sol s))

        =  dterm_sem I (if i = vid1 then Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3)) else Const 0)
                (χ y. if vid3 = y then s else fst (χ y. if vid2 = y then s else fst (ab, bb) $ y, bb) $ y, bb)"
    using mk_v_agree[of "I" "(OSing vid1 (f0 fid1))" "(ab, bb)" "(sol s)"]  vne12 vne23 vne13
    apply(auto simp add: f0_def p1_def empty_def)
    unfolding Vagree_def apply(simp add: f0_def empty_def)
    subgoal for s using thing' by auto
    done
  have allRa':"(∀ra. repv (repv (ab, bb) vid2 t) vid3 ra
               ∈ {v. dterm_sem I (Const 0) v ≤ dterm_sem I (trm.Var vid3) v} ∩
                  {v. dterm_sem I (trm.Var vid3) v ≤ dterm_sem I (trm.Var vid2) v} ⟶
               Predicates I vid2
                (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                (mk_v I (OSing vid1 (f0 fid1)) (ab, bb) (sol ra))))"
    apply(rule allI)
    subgoal for ra
      using mk_v_agree[of "I" "(OSing vid1 (f0 fid1))" "(ab, bb)" "(sol ra)"]
         vne23 constraint[of ra] apply(auto simp add: Vagree_def p1_def)
    done
  done
  have anotherFact:"⋀ra. 0 ≤ ra ⟹ ra ≤ t ⟹ (χ i. if i = vid1 then ab $ i + Functions I fid1 (χ _. 0) * ra else ab $ i) $ vid1 =
     ab $ vid1 + dterm_sem I (f0 fid1) (χ y. if vid3 = y then ra else fst (χ y. if vid2 = y then t else fst (ab, bb) $ y, bb) $ y, bb) * ra "
    subgoal for ra
      apply simp
      apply(rule disjI2)
      by (auto simp add: f0_def empty_def)
    done
  have thing':"⋀ra i. 0 ≤ ra ⟹ ra ≤ t ⟹ dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (ab, bb) (sol ra))
      =  dterm_sem I (if i = vid1 then Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3)) else Const 0)
            (χ y. if vid3 = y then ra else fst (χ y. if vid2 = y then t else fst (ab, bb) $ y, bb) $ y, bb) "
    subgoal for ra i
      using vne12 vne13 mk_v_agree[of I "OSing vid1 ($f fid1 (λi. Const 0))" "(ab,bb)" "(sol ra)"] 
      apply (auto)
      unfolding Vagree_def apply(safe)
      apply(erule allE[where x="vid1"])+
      using sol_eq_exp[of ra] anotherFact[of ra] by auto
    done
  have allRa:"(∀ra. repv (repv (ab, bb) vid2 t) vid3 ra
               ∈ {v. dterm_sem I (Const 0) v ≤ dterm_sem I (trm.Var vid3) v} ∩
                  {v. dterm_sem I (trm.Var vid3) v ≤ dterm_sem I (trm.Var vid2) v} ⟶
               Predicates I vid2
                (χ i. dterm_sem I (singleton (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid3))) i)
                       (repv (repv (ab, bb) vid2 t) vid3 ra)))"
    apply(rule allI)
    subgoal for ra
      using mk_v_agree[of "I" "(OSing vid1 (f0 fid1))" "(ab, bb)" "(sol ra)"]
         vne23 constraint[of ra] apply(auto simp add: Vagree_def p1_def)
      using sol_eq_exp[of ra]  apply (auto simp add: f0_def empty_def Vagree_def vec_eq_iff)
      using thing' by auto
    done
  have fml3:"⋀ra. 0 ≤ ra ⟹ ra ≤ t ⟹
           (∀ω. ω = repv (repv (ab, bb) vid2 t) vid1
                      (dterm_sem I (Plus (trm.Var vid1) (Times (f0 fid1) (trm.Var vid2))) (repv (ab, bb) vid2 t)) ⟶
                 ω ∈ fml_sem I (p1 vid3 vid1))"
    using impl allRa by auto       
  have someEq:"(χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
            (χ y. if vid1 = y then (if vid2 = vid1 then t else fst (ab, bb) $ vid1) + Functions I fid1 (χ i. 0) * t
                  else fst (χ y. if vid2 = y then t else fst (ab, bb) $ y, bb) $ y,
             bb)) 
             = (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (mk_v I (OSing vid1 ($f fid1 (λi. Const 0))) (ab, bb) (sol t)))"
    apply(rule vec_extensionality)
    using vne12 sol_eq_exp t thing by auto
  show "mk_v I (OSing vid1 (f0 fid1)) (ab, bb) (sol t) ∈ fml_sem I (p1 vid3 vid1)"
    using mk_v_agree[of I "OSing vid1 (f0 fid1)" "(ab, bb)" "sol t"] fml3[of t]
    unfolding f0_def p1_def empty_def Vagree_def 
    using someEq by(auto simp add:  sol_eq_exp_t' t vec_extensionality  vne12)
qed qed

lemma MVT0_within:
  fixes f ::"real ⇒ real"
    and f'::"real ⇒ real ⇒ real"
    and s t :: real
  assumes f':"⋀x. x ∈ {0..t} ⟹ (f has_derivative (f' x)) (at x  within {0..t})"
  assumes geq':"⋀x. x ∈ {0..t} ⟹ f' x s ≥ 0"
  assumes int_s:"s > 0 ∧ s ≤ t"
  assumes t: "0 < t"
  shows "f s ≥ f 0"
proof -
  have "f 0 + 0 ≤ f s"   
    apply (rule Lib.MVT_ivl'[OF f', of 0 s 0])
      subgoal for x by assumption
     subgoal for x using geq' by auto 
    using t int_s t apply auto
    subgoal for x
      by (metis int_s mult.commute mult.right_neutral order.trans mult_le_cancel_left_pos)
    done
  then show "?thesis" by auto 
qed

lemma MVT':
  fixes f g ::"real ⇒ real"
  fixes f' g'::"real ⇒ real ⇒ real"
  fixes s t ::real
  assumes f':"⋀s. s ∈ {0..t} ⟹ (f has_derivative (f' s)) (at s within {0..t})"
  assumes g':"⋀s. s ∈ {0..t} ⟹ (g has_derivative (g' s)) (at s within {0..t})"
  assumes geq':"⋀x. x ∈ {0..t} ⟹ f' x s ≥ g' x s"
  assumes geq0:"f 0 ≥ g 0"
  assumes int_s:"s > 0 ∧ s ≤ t"
  assumes t:"t > 0"
  shows "f s ≥ g s"
proof -
  let ?h = "(λx. f x - g x)"
  let ?h' = "(λs x. f' s x - g' s x)"
  have "?h s ≥ ?h 0"
    apply(rule MVT0_within[of t ?h "?h'" s])
       subgoal for s using f'[of s] g'[of s] by auto
      subgoal for sa using geq'[of sa] by auto
     subgoal using int_s by auto
    subgoal using t by auto
    done
  then show "?thesis" using geq0 by auto
qed

lemma MVT'_gr:
  fixes f g ::"real ⇒ real"
  fixes f' g'::"real ⇒ real ⇒ real"
  fixes s t ::real
  assumes f':"⋀s. s ∈ {0..t} ⟹ (f has_derivative (f' s)) (at s within {0..t})"
  assumes g':"⋀s. s ∈ {0..t} ⟹ (g has_derivative (g' s)) (at s within {0..t})"
  assumes geq':"⋀x. x ∈ {0..t} ⟹ f' x s ≥ g' x s"
  assumes geq0:"f 0 > g 0"
  assumes int_s:"s > 0 ∧ s ≤ t"
  assumes t:"t > 0"
  shows "f s > g s"
proof -
  let ?h = "(λx. f x - g x)"
  let ?h' = "(λs x. f' s x - g' s x)"
  have "?h s ≥ ?h 0"
    apply(rule MVT0_within[of t ?h "?h'" s])
       subgoal for s using f'[of s] g'[of s] by auto
      subgoal for sa using geq'[of sa] by auto
     subgoal using int_s by auto
    subgoal using t by auto
    done
  then show "?thesis" using geq0 by auto
qed

lemma frech_linear:
  fixes x θ ν ν' I
  assumes good_interp:"is_interp I"
  assumes free:"dfree θ"
  shows "x * frechet I θ ν ν' = frechet I θ ν (x *⇩R ν')"
  using frechet_linear[OF good_interp free]
  by (simp add: linear_simps)
    
lemma rift_in_space_time:
  fixes sol I ODE ψ θ t s b
  assumes good_interp:"is_interp I"
  assumes free:"dfree θ"
  assumes osafe:"osafe ODE"
  assumes sol:"(sol solves_ode (λ_ ν'. ODE_sem I ODE ν')) {0..t} 
          {x. mk_v I ODE (sol 0, b) x ∈ fml_sem I ψ}"
  assumes FVT:"FVT θ ⊆ semBV I ODE"  
  assumes ivl:"s ∈ {0..t}"
  shows "((λt. sterm_sem I θ (fst (mk_v I ODE (sol 0, b) (sol t))))
    ― ‹This is Frechet derivative, so equivalent to:›
    ― ‹‹has_real_derivative frechet I θ (fst((mk_v I ODE (sol 0, b) (sol s)))) (snd (mk_v I ODE (sol 0, b) (sol s))))) (at s within {0..t})››
    has_derivative (λt'. t' * frechet I θ (fst((mk_v I ODE (sol 0, b) (sol s)))) (snd (mk_v I ODE (sol 0, b) (sol s))))) (at s within {0..t})"
proof -
  let ?φ = "(λt. (mk_v I ODE (sol 0, b) (sol t)))"
  let ?φs = "(λt. fst (?φ t))"
  have sol_deriv:"⋀s. s ∈ {0..t} ⟹ (sol has_derivative (λxa. xa *⇩R ODE_sem I ODE (sol s))) (at s within {0..t})"
    using sol apply simp 
    apply (drule solves_odeD(1))
    unfolding has_vderiv_on_def has_vector_derivative_def
    by auto
  have sol_dom:"⋀s. s∈ {0..t} ⟹ ?φ s ∈ fml_sem I ψ"
    using sol apply simp
    apply (drule solves_odeD(2))
     by auto
  let ?h = "(λt. sterm_sem I θ (?φs t))"
  let ?g = "(λν. sterm_sem I θ ν)"
  let ?f = "?φs"
  let ?f' = "(λt'. t' *⇩R (χ i. if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol s) $ i else 0))"
  let ?g' = "(frechet I θ (?φs s))"
  have heq:"?h = ?g ∘ ?f" by (auto)
  have fact1:"⋀i. i ∈ ODE_vars I ODE ⟹ (λt. ?φs(t) $ i) = (λt. sol t $ i)"
    subgoal for i
      apply(rule ext)
      subgoal for t
        using mk_v_agree[of I ODE "(sol 0, b)" "sol t"]
        unfolding Vagree_def by auto
      done done
  have fact2:"⋀i. i ∈ ODE_vars I ODE ⟹ (λt. if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol t) $ i else 0) = (λt. ODE_sem I ODE (sol t) $ i)"
    subgoal for i
      apply(rule ext)
      subgoal for t
        using mk_v_agree[of I ODE "(sol 0, b)" "sol t"]
        unfolding Vagree_def by auto
      done done
  have fact3:"⋀i. i ∈ (-ODE_vars I ODE) ⟹ (λt. ?φs(t) $ i) = (λt. sol 0 $ i)"
    subgoal for i
      apply(rule ext)
      subgoal for t
        using mk_v_agree[of I ODE "(sol 0, b)" "sol t"]
        unfolding Vagree_def by auto
      done done
  have fact4:"⋀i. i ∈ (-ODE_vars I ODE) ⟹ (λt. if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol t) $ i else 0) = (λt. 0)"
    subgoal for i
      apply(rule ext)
      subgoal for t
        using mk_v_agree[of I ODE "(sol 0, b)" "sol t"]
        unfolding Vagree_def by auto
      done done
  have some_eq:"(λv'. χ i. v' *⇩R ODE_sem I ODE (sol s) $ i) = (λv'. v' *⇩R ODE_sem I ODE (sol s))"
    apply(rule ext)
    apply(rule vec_extensionality)
    by auto
  have some_sol:"(sol has_derivative (λv'. v' *⇩R ODE_sem I ODE (sol s))) (at s within {0..t})"
    using sol ivl unfolding solves_ode_def has_vderiv_on_def has_vector_derivative_def by auto
  have some_eta:"(λt. χ i. sol t $ i) = sol" by (rule ext, rule vec_extensionality, auto)
  have ode_deriv:"⋀i. i ∈ ODE_vars I ODE ⟹ 
    ((λt. sol t $ i) has_derivative (λ v'. v' *⇩R ODE_sem I ODE (sol s) $ i)) (at s within {0..t})"
    subgoal for i
      apply(rule has_derivative_proj)
      using some_eq some_sol some_eta by auto
    done
  have eta:"(λt. (χ i. ?f t $ i)) = ?f" by(rule ext, rule vec_extensionality, auto)
  have eta_esque:"(λt'. χ i. t' * (if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol s) $ i else 0)) =  
                  (λt'. t' *⇩R (χ i. if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol s) $ i else 0))"
    apply(rule ext | rule vec_extensionality)+
    subgoal for t' i by auto done
  have "((λt. (χ i. ?f t $ i)) has_derivative (λt'. (χ i. ?f' t' $ i))) (at s within {0..t})"
    apply (rule has_derivative_vec)
    subgoal for i       
      apply(cases "i ∈ ODE_vars I ODE")
       subgoal using fact1[of i] fact2[of i] ode_deriv[of i] by auto 
      subgoal using fact3[of i] fact4[of i] by auto 
    done
  done
  then have fderiv:"(?f has_derivative ?f') (at s within {0..t})" using eta eta_esque by auto
  have gderiv:"(?g has_derivative ?g') (at (?f s) within ?f ` {0..t})"
     using has_derivative_at_withinI 
     using frechet_correctness free good_interp 
     by blast
  have chain:"((?g ∘ ?f) has_derivative (?g' ∘ ?f')) (at s within {0..t})"
    using fderiv gderiv diff_chain_within by blast
  let ?coν1 = "(fst (mk_v I ODE (sol 0, b) (sol s)), ODE_sem I ODE (fst (mk_v I ODE (sol 0, b) (sol s))))"
  let ?coν2 = "(fst (mk_v I ODE (sol 0, b) (sol s)), snd (mk_v I ODE (sol 0, b) (sol s)))"
  have sub_cont:"⋀a .a ∉ ODE_vars I ODE ⟹ Inl a ∈ FVT θ ⟹ False"
    using FVT by auto
  have sub_cont2:"⋀a .a ∉ ODE_vars I ODE ⟹ Inr a ∈ FVT θ ⟹ False"
    using FVT by auto
  have "Vagree (mk_v I ODE (sol 0, b) (sol s)) (sol s, b) (Inl ` ODE_vars I ODE)"
    using mk_v_agree[of I ODE "(sol 0, b)" "sol s"]
    unfolding Vagree_def by auto
  let ?co'ν1 = "(λx. (fst (mk_v I ODE (sol 0, b) (sol s)), x *⇩R (χ i. if i ∈ ODE_vars I ODE then ODE_sem I ODE (sol s) $ i else 0)))"
  let ?co'ν2 = "(λx. (fst (mk_v I ODE (sol 0, b) (sol s)), x *⇩R snd (mk_v I ODE (sol 0, b) (sol s))))"
  have co_agree_sem:"⋀s. Vagree (?co'ν1 s) (?co'ν2 s) (semBV I ODE)"
    subgoal for sa
      using mk_v_agree[of I ODE "(sol 0, b)" "sol s"]
      unfolding Vagree_def by auto
    done
  have co_agree_help:"⋀s. Vagree (?co'ν1 s) (?co'ν2 s) (FVT θ)"
    using agree_sub[OF FVT co_agree_sem] by auto
  have co_agree':"⋀s. Vagree (?co'ν1 s) (?co'ν2 s) (FVDiff θ)"
    subgoal for s
      using mk_v_agree[of I ODE "(sol 0, b)" "sol s"]
      unfolding Vagree_def apply auto
      subgoal for i x
        apply(cases x)
        subgoal for a
          apply(cases "a ∈ ODE_vars I ODE")
           by (simp | metis (no_types, lifting) FVT ODE_vars_lr Vagree_def mk_v_agree mk_xode.elims subsetD snd_conv)+
        subgoal for a
          apply(cases "a ∈ ODE_vars I ODE")
           by (simp | metis (no_types, lifting) FVT Vagree_def mk_v_agree mk_xode.elims subsetD snd_conv)+
        done
      subgoal for i x
        apply(cases x)
        subgoal for a
          apply(cases "a ∈ ODE_vars I ODE")
           using FVT ODE_vars_lr Vagree_def mk_v_agree mk_xode.elims subsetD snd_conv
           by auto
        subgoal for a
          apply(cases "a ∈ ODE_vars I ODE")
           apply(erule allE[where x=i])+
           using FVT ODE_vars_lr Vagree_def mk_v_agree mk_xode.elims subsetD snd_conv
           by auto
        done
      done
    done 
  have heq'':"(?g' ∘ ?f') = (λt'. t' *⇩R frechet I θ (?φs s) (snd (?φ s)))"
    using mk_v_agree[of I ODE "(sol 0, b)" "sol s"]
    unfolding comp_def
    apply auto
    apply(rule ext | rule vec_extensionality)+
    subgoal for x
      using frech_linear[of I θ x "(fst (mk_v I ODE (sol 0, b) (sol s)))" "(snd (mk_v I ODE (sol 0, b) (sol s)))", OF good_interp free]
      using coincidence_frechet[OF free, of "(?co'ν1 x)" "(?co'ν2 x)", OF co_agree'[of x], of I]
      by auto
    done
  have "((?g ∘ ?f) has_derivative (?g' ∘ ?f')) (at s within {0..t})"
    using chain by auto
  then have "((?g ∘ ?f) has_derivative (λt'. t' * frechet I θ (?φs s) (snd (?φ s)))) (at s within {0..t})"
    using heq'' by auto
  then have result:"((λt. sterm_sem I θ (?φs t))  has_derivative (λt. t * frechet I θ (?φs s) (snd (?φ s)))) (at s within {0..t})"
    using heq by auto
  then show "?thesis" by auto
qed

lemma dterm_sterm_dfree:
   "dfree θ ⟹ (⋀ν ν'. sterm_sem I θ ν = dterm_sem I θ (ν, ν'))"
  by(induction rule: dfree.induct, auto)

― ‹‹g(x)≥ h(x) →  [x'=f(x), c & p(x)](g(x)' ≥ h(x)') → [x'=f(x), c]g(x) ≥ h(x)››  
lemma DIGeq_valid:"valid DIGeqaxiom"
  unfolding DIGeqaxiom_def
  apply(unfold DIGeqaxiom_def valid_def impl_sem iff_sem)
  apply(auto) (* 4 goals*)
  proof -
    fix I::"('sf,'sc,'sz) interp" and  b aa ba 
      and sol::"real ⇒ 'sz simple_state" 
      and t::real
    let ?ODE = "OVar vid1"
    let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
    assume t:"0 ≤ t"
      and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
      {x. Predicates I vid1 (χ i. dterm_sem I (empty i) (mk_v I ?ODE (sol 0, b) x))}"
      and notin:" ¬(Predicates I vid1 (χ i. dterm_sem I (empty i) (sol 0, b)))"
    have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
    from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
      using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
    then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
      using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
      unfolding Vagree_def by (auto simp add: empty_def)
    show "dterm_sem I (f1 fid2 vid1)  (mk_v I (OVar vid1) (sol 0, b) (sol t)) ≤ dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
      using notin incon by auto
  next
    fix I::"('sf,'sc,'sz) interp" and  b aa ba 
      and sol::"real ⇒ 'sz simple_state" 
      and t::real
    let ?ODE = "OVar vid1"
    let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
    assume t:"0 ≤ t"
      and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
      {x. Predicates I vid1 (χ i. dterm_sem I (empty i) (mk_v I ?ODE (sol 0, b) x))}"
      and notin:" ¬(Predicates I vid1 (χ i. dterm_sem I (empty i) (sol 0, b)))"
    have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
    from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
      using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
    then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
      using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
      unfolding Vagree_def by (auto simp add: empty_def)
    show "dterm_sem I (f1 fid2 vid1)  (mk_v I (OVar vid1) (sol 0, b) (sol t)) ≤ dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
      using notin incon by auto
  next
    fix I::"('sf,'sc,'sz) interp" and  b aa ba 
      and sol::"real ⇒ 'sz simple_state" 
      and t::real
    let ?ODE = "OVar vid1"
    let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
    assume t:"0 ≤ t"
    assume sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
        {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}"
    assume notin:"¬ Predicates I vid1 (χ i. dterm_sem I (local.empty i) (sol 0, b))"
    have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
    from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
      using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
    then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
      using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
      unfolding Vagree_def by (auto simp add: empty_def)
    show "dterm_sem I (f1 fid2 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))
       ≤ dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
      using incon notin by auto
next
    fix I::"('sf,'sc,'sz) interp" and  b aa ba 
      and sol::"real ⇒ 'sz simple_state" 
      and t::real
    let ?ODE = "OVar vid1"
    let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
    assume good_interp:"is_interp I"
    assume aaba:"(aa, ba) = mk_v I (OVar vid1) (sol 0, b) (sol t)"
    assume t:"0 ≤ t"
    assume sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
        {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}"
    assume box:"∀a ba. (∃sola. sol 0 = sola 0 ∧
                      (∃t. (a, ba) = mk_v I (OVar vid1) (sola 0, b) (sola t) ∧
                           0 ≤ t ∧
                           (sola solves_ode (λa. ODEs I vid1)) {0..t}
                            {x. Predicates I vid1
                                 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sola 0, b) x))})) ⟶
              directional_derivative I (f1 fid2 vid1) (a, ba) ≤ directional_derivative I (f1 fid1 vid1) (a, ba)"
    assume geq0:"dterm_sem I (f1 fid2 vid1) (sol 0, b) ≤ dterm_sem I (f1 fid1 vid1) (sol 0, b)"
    have free1:"dfree ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
      by (auto intro: dfree.intros)
    have free2:"dfree ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
      by (auto intro: dfree.intros)
    from geq0 
    have geq0':"sterm_sem I (f1 fid2 vid1) (sol 0) ≤ sterm_sem I (f1 fid1 vid1) (sol 0)"
      unfolding f1_def using dterm_sterm_dfree[OF free1, of I "sol 0" b] dterm_sterm_dfree[OF free2, of I "sol 0" b] 
      by auto  
    let ?φs = "λx. fst (?φ x)"
    let ?φt = "λx. snd (?φ x)"
    let ?df1 = "(λt. dterm_sem I (f1 fid2 vid1) (?φ t))"
    let ?f1 = "(λt. sterm_sem I (f1 fid2 vid1) (?φs t))"
    let ?f1' = "(λ s t'. t' * frechet I (f1 fid2 vid1) (?φs s) (?φt s))"
    have dfeq:"?df1 = ?f1" 
      apply(rule ext)
      subgoal for t
        using dterm_sterm_dfree[OF free1, of I "?φs t" "snd (?φ t)"] unfolding f1_def expand_singleton by auto
      done
    have free3:"dfree (f1 fid2 vid1)" unfolding f1_def by (auto intro: dfree.intros)
    let ?df2 = "(λt. dterm_sem I (f1 fid1 vid1) (?φ t))"
    let ?f2 = "(λt. sterm_sem I (f1 fid1 vid1) (?φs t))"
    let ?f2' = "(λs t' . t' * frechet I (f1 fid1 vid1) (?φs s) (?φt s))"
    let ?int = "{0..t}"
    have bluh:"⋀x i. (Functions I i has_derivative (THE f'. ∀x. (Functions I i has_derivative f' x) (at x)) x) (at x)"
      using good_interp unfolding is_interp_def by auto
    have blah:"(Functions I fid2 has_derivative (THE f'. ∀x. (Functions I fid2 has_derivative f' x) (at x)) (χ i. if i = vid1 then sol t $ vid1 else 0)) (at (χ i. if i = vid1 then sol t $ vid1 else 0))"
      using bluh by auto
    have bigEx:"⋀s. s ∈ {0..t} ⟹(∃sola. sol 0 = sola 0 ∧
         (∃ta. (fst (?φ s),
                snd (?φ s)) =
               mk_v I (OVar vid1) (sola 0, b) (sola ta) ∧
               0 ≤ ta ∧
               (sola solves_ode (λa. ODEs I vid1)) {0..ta}
                {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}))"
      subgoal for s
        apply(rule exI[where x=sol])
        apply(rule conjI)
         subgoal by (rule refl)
        apply(rule exI[where x=s])
        apply(rule conjI)
         subgoal by auto 
        apply(rule conjI)
         subgoal by auto
        using sol
        using atLeastAtMost_iff atLeastatMost_subset_iff order_refl solves_ode_on_subset
        by (metis (no_types, lifting) subsetI)
      done
    have box':"⋀s. s ∈ {0..t} ⟹ directional_derivative I (f1 fid2 vid1) (?φs s, ?φt s) 
                                ≤ directional_derivative I (f1 fid1 vid1) (?φs s, ?φt s)"
      subgoal for s
      using box 
      apply simp
      apply (erule allE[where x="?φs s"])
      apply (erule allE[where x="?φt s"])
      using bigEx[of s] by auto 
    done
    have dsafe1:"dsafe (f1 fid2 vid1)" unfolding f1_def by (auto intro: dsafe.intros)
    have dsafe2:"dsafe (f1 fid1 vid1)" unfolding f1_def by (auto intro: dsafe.intros)
    have agree1:"Vagree (sol 0, b) (?φ 0) (FVT (f1 fid2 vid1))"
      using mk_v_agree[of I "(OVar vid1)" "(sol 0, b)" "fst (?φ 0)"]
      unfolding f1_def Vagree_def expand_singleton 
      apply auto
      by (metis (no_types, lifting) Compl_iff Vagree_def fst_conv mk_v_agree mk_xode.simps semBV.simps)
    have agree2:"Vagree (sol 0, b) (?φ 0) (FVT (f1 fid1 vid1))"
      using mk_v_agree[of I "(OVar vid1)" "(sol 0, b)" "fst (?φ 0)"]
      unfolding f1_def Vagree_def expand_singleton 
      apply auto
      by (metis (no_types, lifting) Compl_iff Vagree_def fst_conv mk_v_agree mk_xode.simps semBV.simps)
    have sem_eq1:"dterm_sem I (f1 fid2 vid1) (sol 0, b) = dterm_sem I (f1 fid2 vid1) (?φ 0)"
      using coincidence_dterm[OF dsafe1 agree1] by auto
    then have sem_eq1':"sterm_sem I (f1 fid2 vid1) (sol 0) = sterm_sem I (f1 fid2 vid1) (?φs 0)"
      using dterm_sterm_dfree[OF free1, of I "sol 0" "b"] 
            dterm_sterm_dfree[OF free1, of I "(?φs 0)" "snd (?φ 0)"]
      unfolding f1_def expand_singleton by auto
    have sem_eq2:"dterm_sem I (f1 fid1 vid1) (sol 0, b) = dterm_sem I (f1 fid1 vid1) (?φ 0)"
      using coincidence_dterm[OF dsafe2 agree2] by auto
    then have sem_eq2':"sterm_sem I (f1 fid1 vid1) (sol 0) = sterm_sem I (f1 fid1 vid1) (?φs 0)" 
      using dterm_sterm_dfree[OF free2, of I "sol 0" "b"] dterm_sterm_dfree[OF free2, of I "(?φs 0)" "snd (?φ 0)"]
      unfolding f1_def expand_singleton by auto
    have good_interp':"⋀i x. (Functions I i has_derivative (THE f'. ∀x. (Functions I i has_derivative f' x) (at x)) x) (at x)"
      using good_interp unfolding is_interp_def by auto
    have chain :  
      "⋀f f' g g' x s.
        (f has_derivative f') (at x within s) ⟹
        (g has_derivative g') (at (f x) within f ` s) ⟹ (g ∘ f has_derivative g' ∘ f') (at x within s)"
      by(auto intro: derivative_intros)
    have sol1:"(sol solves_ode (λ_. ODE_sem I (OVar vid1))) {0..t} {x. mk_v I (OVar vid1) (sol 0, b) x ∈ fml_sem I (Prop vid1 empty)}"
      using sol unfolding p1_def singleton_def empty_def by auto
    have FVTsub1:"vid1 ∈ ODE_vars I (OVar vid1) ⟹ FVT ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ⊆ semBV I ((OVar vid1))"
      apply auto
      subgoal for x xa
        apply(cases "xa = vid1")
         by auto
      done
    have FVTsub2:"vid1 ∈ ODE_vars I (OVar vid1) ⟹ FVT ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ⊆ semBV I ((OVar vid1))"
      apply auto
      subgoal for x xa
        apply(cases "xa = vid1")
         by auto
      done
    have osafe:"osafe (OVar vid1)"
      by auto
    have deriv1:"⋀s. vid1 ∈ ODE_vars I (OVar vid1) ⟹ s ∈ ?int ⟹ (?f1 has_derivative (?f1' s)) (at s within {0..t})"
      subgoal for s
        using  rift_in_space_time[OF good_interp free1 osafe sol1 FVTsub1, of s]
        unfolding f1_def expand_singleton directional_derivative_def
        by blast
      done
    have deriv2:"⋀s. vid1 ∈ ODE_vars I (OVar vid1) ⟹ s ∈ ?int ⟹ (?f2 has_derivative (?f2' s)) (at s within {0..t})"
      subgoal for s
        using rift_in_space_time[OF good_interp free2 osafe sol1 FVTsub2, of s] 
        unfolding f1_def expand_singleton directional_derivative_def
        by blast
      done
    have leq:"⋀s . s ∈ ?int ⟹ ?f1' s 1 ≤ ?f2' s 1"
      subgoal for s using box'[of s] 
        by (simp add: directional_derivative_def)
      done
    have preserve_agree1:"vid1 ∉ ODE_vars I (OVar vid1) ⟹ VSagree (sol 0) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t))) {vid1}"
      using mk_v_agree[of I "OVar vid1" "(sol 0, b)" "sol t"]
      unfolding Vagree_def VSagree_def
      by auto
    have preserve_coincide1:
      "vid1 ∉ ODE_vars I (OVar vid1) ⟹ 
      sterm_sem I (f1 fid2 vid1) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t)))
     = sterm_sem I (f1 fid2 vid1) (sol 0)" 
      using coincidence_sterm[of "(sol 0, b)" "(mk_v I (OVar vid1) (sol 0, b) (sol t))" "f1 fid2 vid1" I]
      preserve_agree1 unfolding VSagree_def Vagree_def f1_def by auto
    have preserve_coincide2:
      "vid1 ∉ ODE_vars I (OVar vid1) ⟹ 
      sterm_sem I (f1 fid1 vid1) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t)))
     = sterm_sem I (f1 fid1 vid1) (sol 0)" 
      using coincidence_sterm[of "(sol 0, b)" "(mk_v I (OVar vid1) (sol 0, b) (sol t))" "f1 fid1 vid1" I]
      preserve_agree1 unfolding VSagree_def Vagree_def f1_def by auto
    have "?f1 t ≤ ?f2 t"
      apply(cases "t = 0")
       subgoal using geq0' sem_eq1' sem_eq2' by auto  
      subgoal
        apply(cases "vid1 ∈ ODE_vars I (OVar vid1)")
        subgoal
          apply (rule MVT'[OF deriv2 deriv1, of t]) (* 8 subgoals *)
                 subgoal by auto
                subgoal by auto
               subgoal for s using deriv2[of s] using leq by auto
              using t leq geq0' sem_eq1' sem_eq2' by auto
        subgoal
          using geq0 
          using dterm_sterm_dfree[OF free1, of I "sol 0" "b"]
          using dterm_sterm_dfree[OF free2, of I "sol 0" "b"]
          using preserve_coincide1 preserve_coincide2
          by(simp add: f1_def)
        done
      done
    then 
    show "       dterm_sem I (f1 fid2 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))
       ≤ dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))
"
      using t 
      dterm_sterm_dfree[OF free2, of I "?φs t" "snd (?φ t)"]
      dterm_sterm_dfree[OF free1, of I "?φs t" "snd (?φ t)"]
      by (simp add: f1_def)
qed 
  
  
lemma DIGr_valid:"valid DIGraxiom"
  unfolding DIGraxiom_def
  apply(unfold DIGraxiom_def valid_def impl_sem iff_sem)
  apply(auto) (* 4 subgoals*)
proof -
  fix I::"('sf,'sc,'sz) interp" and  b aa ba 
    and sol::"real ⇒ 'sz simple_state" 
    and t::real
  let ?ODE = "OVar vid1"
  let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
  assume t:"0 ≤ t"
    and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
    {x. Predicates I vid1 (χ i. dterm_sem I (empty i) (mk_v I ?ODE (sol 0, b) x))}"
    and notin:" ¬(Predicates I vid1 (χ i. dterm_sem I (empty i) (sol 0, b)))"
  have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
  from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
    using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
  then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
    using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
    unfolding Vagree_def by (auto simp add: empty_def)
  show "dterm_sem I (f1 fid2 vid1)  (mk_v I (OVar vid1) (sol 0, b) (sol t)) < dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
    using notin incon by auto
next
  fix I::"('sf,'sc,'sz) interp" and  b aa ba 
    and sol::"real ⇒ 'sz simple_state" 
    and t::real
  let ?ODE = "OVar vid1"
  let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
  assume t:"0 ≤ t"
    and sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
    {x. Predicates I vid1 (χ i. dterm_sem I (empty i) (mk_v I ?ODE (sol 0, b) x))}"
    and notin:" ¬(Predicates I vid1 (χ i. dterm_sem I (empty i) (sol 0, b)))"
  have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
  from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
    using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
  then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
    using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
    unfolding Vagree_def by (auto simp add: empty_def)
  show "dterm_sem I (f1 fid2 vid1)  (mk_v I (OVar vid1) (sol 0, b) (sol t)) < dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
    using notin incon by auto
next
  fix I::"('sf,'sc,'sz) interp" and  b aa ba 
    and sol::"real ⇒ 'sz simple_state" 
    and t::real
  let ?ODE = "OVar vid1"
  let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
  assume t:"0 ≤ t"
  assume sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
      {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}"
  assume notin:"¬ Predicates I vid1 (χ i. dterm_sem I (local.empty i) (sol 0, b))"
  have fsafe:"fsafe (Prop vid1 empty)" by (auto simp add: empty_def)
  from sol have "Predicates I vid1 (χ i. dterm_sem I (empty i) (?φ 0))"
    using t solves_ode_domainD[of sol "(λa. ODEs I vid1)" "{0..t}"]  by auto
  then have incon:"Predicates I vid1 (χ i. dterm_sem I (empty i) ((sol 0, b)))"
    using coincidence_formula[OF fsafe Iagree_refl[of I], of "(sol 0, b)" "?φ 0"]
    unfolding Vagree_def by (auto simp add: empty_def) 
  show "dterm_sem I (f1 fid2 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))
     < dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
    using incon notin by auto
next
  fix I::"('sf,'sc,'sz) interp" and  b aa ba 
  and sol::"real ⇒ 'sz simple_state" 
  and t::real
  let ?ODE = "OVar vid1"
  let ?φ = "(λt. mk_v I (?ODE) (sol 0, b) (sol t))"
  assume good_interp:"is_interp I"
  assume aaba:"(aa, ba) = mk_v I (OVar vid1) (sol 0, b) (sol t)"
  assume t:"0 ≤ t"
  assume sol:"(sol solves_ode (λa. ODEs I vid1)) {0..t}
      {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}"
  assume box:"∀a ba. (∃sola. sol 0 = sola 0 ∧
                    (∃t. (a, ba) = mk_v I (OVar vid1) (sola 0, b) (sola t) ∧
                         0 ≤ t ∧
                         (sola solves_ode (λa. ODEs I vid1)) {0..t}
                          {x. Predicates I vid1
                               (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sola 0, b) x))})) ⟶
            directional_derivative I (f1 fid2 vid1) (a, ba) ≤ directional_derivative I (f1 fid1 vid1) (a, ba)"
  assume geq0:"dterm_sem I (f1 fid2 vid1) (sol 0, b) < dterm_sem I (f1 fid1 vid1) (sol 0, b)"
  have free1:"dfree ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
    by (auto intro: dfree.intros)
  have free2:"dfree ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
    by (auto intro: dfree.intros)
  from geq0 
  have geq0':"sterm_sem I (f1 fid2 vid1) (sol 0) < sterm_sem I (f1 fid1 vid1) (sol 0)"
    unfolding f1_def using dterm_sterm_dfree[OF free1, of I "sol 0" b] dterm_sterm_dfree[OF free2, of I "sol 0" b] 
    by auto  
  let ?φs = "λx. fst (?φ x)"
  let ?φt = "λx. snd (?φ x)"
  let ?df1 = "(λt. dterm_sem I (f1 fid2 vid1) (?φ t))"
  let ?f1 = "(λt. sterm_sem I (f1 fid2 vid1) (?φs t))"
  let ?f1' = "(λ s t'. t' * frechet I (f1 fid2 vid1) (?φs s) (?φt s))"
  have dfeq:"?df1 = ?f1" 
    apply(rule ext)
    subgoal for t
      using dterm_sterm_dfree[OF free1, of I "?φs t" "snd (?φ t)"] unfolding f1_def expand_singleton by auto
    done
  have free3:"dfree (f1 fid2 vid1)" unfolding f1_def by (auto intro: dfree.intros)
  let ?df2 = "(λt. dterm_sem I (f1 fid1 vid1) (?φ t))"
  let ?f2 = "(λt. sterm_sem I (f1 fid1 vid1) (?φs t))"
  let ?f2' = "(λs t' . t' * frechet I (f1 fid1 vid1) (?φs s) (?φt s))"
  let ?int = "{0..t}"
  have bluh:"⋀x i. (Functions I i has_derivative (THE f'. ∀x. (Functions I i has_derivative f' x) (at x)) x) (at x)"
    using good_interp unfolding is_interp_def by auto
  have blah:"(Functions I fid2 has_derivative (THE f'. ∀x. (Functions I fid2 has_derivative f' x) (at x)) (χ i. if i = vid1 then sol t $ vid1 else 0)) (at (χ i. if i = vid1 then sol t $ vid1 else 0))"
    using bluh by auto
  have bigEx:"⋀s. s ∈ {0..t} ⟹(∃sola. sol 0 = sola 0 ∧
       (∃ta. (fst (?φ s),
              snd (?φ s)) =
             mk_v I (OVar vid1) (sola 0, b) (sola ta) ∧
             0 ≤ ta ∧
             (sola solves_ode (λa. ODEs I vid1)) {0..ta}
              {x. Predicates I vid1 (χ i. dterm_sem I (local.empty i) (mk_v I (OVar vid1) (sol 0, b) x))}))"
    subgoal for s
      apply(rule exI[where x=sol])
      apply(rule conjI)
       subgoal by (rule refl)
      apply(rule exI[where x=s])
      apply(rule conjI)
       subgoal by auto 
      apply(rule conjI)
       subgoal by auto
      using sol
      using atLeastAtMost_iff atLeastatMost_subset_iff order_refl solves_ode_on_subset
      by (metis (no_types, lifting) subsetI)
    done
  have box':"⋀s. s ∈ {0..t} ⟹ directional_derivative I (f1 fid2 vid1) (?φs s, ?φt s) 
                              ≤ directional_derivative I (f1 fid1 vid1) (?φs s, ?φt s)"
    subgoal for s
    using box 
    apply simp
    apply (erule allE[where x="?φs s"])
    apply (erule allE[where x="?φt s"])
    using bigEx[of s] by auto 
  done
  have dsafe1:"dsafe (f1 fid2 vid1)" unfolding f1_def by (auto intro: dsafe.intros)
  have dsafe2:"dsafe (f1 fid1 vid1)" unfolding f1_def by (auto intro: dsafe.intros)
  have agree1:"Vagree (sol 0, b) (?φ 0) (FVT (f1 fid2 vid1))"
    using mk_v_agree[of I "(OVar vid1)" "(sol 0, b)" "fst (?φ 0)"]
    unfolding f1_def Vagree_def expand_singleton 
    apply auto
    by (metis (no_types, lifting) Compl_iff Vagree_def fst_conv mk_v_agree mk_xode.simps semBV.simps)
  have agree2:"Vagree (sol 0, b) (?φ 0) (FVT (f1 fid1 vid1))"
    using mk_v_agree[of I "(OVar vid1)" "(sol 0, b)" "fst (?φ 0)"]
    unfolding f1_def Vagree_def expand_singleton 
    apply auto
    by (metis (no_types, lifting) Compl_iff Vagree_def fst_conv mk_v_agree mk_xode.simps semBV.simps)
  have sem_eq1:"dterm_sem I (f1 fid2 vid1) (sol 0, b) = dterm_sem I (f1 fid2 vid1) (?φ 0)"
    using coincidence_dterm[OF dsafe1 agree1] by auto
  then have sem_eq1':"sterm_sem I (f1 fid2 vid1) (sol 0) = sterm_sem I (f1 fid2 vid1) (?φs 0)"
    using dterm_sterm_dfree[OF free1, of I "sol 0" "b"] 
          dterm_sterm_dfree[OF free1, of I "(?φs 0)" "snd (?φ 0)"]
    unfolding f1_def expand_singleton by auto
  have sem_eq2:"dterm_sem I (f1 fid1 vid1) (sol 0, b) = dterm_sem I (f1 fid1 vid1) (?φ 0)"
    using coincidence_dterm[OF dsafe2 agree2] by auto
  then have sem_eq2':"sterm_sem I (f1 fid1 vid1) (sol 0) = sterm_sem I (f1 fid1 vid1) (?φs 0)" 
    using dterm_sterm_dfree[OF free2, of I "sol 0" "b"] dterm_sterm_dfree[OF free2, of I "(?φs 0)" "snd (?φ 0)"]
    unfolding f1_def expand_singleton by auto
  have good_interp':"⋀i x. (Functions I i has_derivative (THE f'. ∀x. (Functions I i has_derivative f' x) (at x)) x) (at x)"
    using good_interp unfolding is_interp_def by auto
  have chain :  
    "⋀f f' g g' x s.
      (f has_derivative f') (at x within s) ⟹
      (g has_derivative g') (at (f x) within f ` s) ⟹ (g ∘ f has_derivative g' ∘ f') (at x within s)"
    by(auto intro: derivative_intros)
  have sol1:"(sol solves_ode (λ_. ODE_sem I (OVar vid1))) {0..t} {x. mk_v I (OVar vid1) (sol 0, b) x ∈ fml_sem I (Prop vid1 empty)}"
    using sol unfolding p1_def singleton_def empty_def by auto
  have FVTsub1:"vid1 ∈ ODE_vars I (OVar vid1) ⟹ FVT ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ⊆ semBV I ((OVar vid1))"
    apply auto
    subgoal for x xa
      apply(cases "xa = vid1")
       by auto
    done
  have FVTsub2:"vid1 ∈ ODE_vars I (OVar vid1) ⟹ FVT ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) ⊆ semBV I ((OVar vid1))"
    apply auto
    subgoal for x xa
      apply(cases "xa = vid1")
       by auto
    done
  have osafe:"osafe (OVar vid1)"
    by auto
  have deriv1:"⋀s. vid1 ∈ ODE_vars I (OVar vid1) ⟹ s ∈ ?int ⟹ (?f1 has_derivative (?f1' s)) (at s within {0..t})"
    subgoal for s
      using  rift_in_space_time[OF good_interp free1 osafe sol1 FVTsub1, of s]
      unfolding f1_def expand_singleton directional_derivative_def
      by blast
    done
  have deriv2:"⋀s. vid1 ∈ ODE_vars I (OVar vid1) ⟹ s ∈ ?int ⟹ (?f2 has_derivative (?f2' s)) (at s within {0..t})"
    subgoal for s
      using rift_in_space_time[OF good_interp free2 osafe sol1 FVTsub2, of s] 
      unfolding f1_def expand_singleton directional_derivative_def
      by blast
    done
  have leq:"⋀s . s ∈ ?int ⟹ ?f1' s 1 ≤ ?f2' s 1"
    subgoal for s using box'[of s] 
      by (simp add: directional_derivative_def)
    done
  have preserve_agree1:"vid1 ∉ ODE_vars I (OVar vid1) ⟹ VSagree (sol 0) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t))) {vid1}"
    using mk_v_agree[of I "OVar vid1" "(sol 0, b)" "sol t"]
    unfolding Vagree_def VSagree_def
    by auto
  have preserve_coincide1:
    "vid1 ∉ ODE_vars I (OVar vid1) ⟹ 
    sterm_sem I (f1 fid2 vid1) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t)))
   = sterm_sem I (f1 fid2 vid1) (sol 0)" 
    using coincidence_sterm[of "(sol 0, b)" "(mk_v I (OVar vid1) (sol 0, b) (sol t))" "f1 fid2 vid1" I]
    preserve_agree1 unfolding VSagree_def Vagree_def f1_def by auto
  have preserve_coincide2:
    "vid1 ∉ ODE_vars I (OVar vid1) ⟹ 
    sterm_sem I (f1 fid1 vid1) (fst (mk_v I (OVar vid1) (sol 0, b) (sol t)))
   = sterm_sem I (f1 fid1 vid1) (sol 0)" 
    using coincidence_sterm[of "(sol 0, b)" "(mk_v I (OVar vid1) (sol 0, b) (sol t))" "f1 fid1 vid1" I]
    preserve_agree1 unfolding VSagree_def Vagree_def f1_def by auto
  have "?f1 t < ?f2 t"
    apply(cases "t = 0")
     subgoal using geq0' sem_eq1' sem_eq2' by auto  
    subgoal
      apply(cases "vid1 ∈ ODE_vars I (OVar vid1)")
      subgoal
        apply (rule MVT'_gr[OF deriv2 deriv1, of t])
               subgoal by auto
              subgoal by auto
             subgoal for s using deriv2[of s] using leq by auto
            using t leq geq0' sem_eq1' sem_eq2' by auto
      subgoal
        using geq0 
        using dterm_sterm_dfree[OF free1, of I "sol 0" "b"]
        using dterm_sterm_dfree[OF free2, of I "sol 0" "b"]
        using preserve_coincide1 preserve_coincide2
        by(simp add: f1_def)
      done
    done
  then 
  show "dterm_sem I (f1 fid2 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))
     < dterm_sem I (f1 fid1 vid1) (mk_v I (OVar vid1) (sol 0, b) (sol t))"
    using t 
    dterm_sterm_dfree[OF free2, of I "?φs t" "snd (?φ t)"]
    dterm_sterm_dfree[OF free1, of I "?φs t" "snd (?φ t)"]
    using geq0 f1_def
    by (simp add: f1_def)
qed 

lemma DG_valid:"valid DGaxiom"
proof -
  have osafe:"osafe (OSing vid1 (f1 fid1 vid1))" 
    by(auto simp add: osafe_Sing dfree_Fun dfree_Const f1_def expand_singleton)
  have fsafe:"fsafe (p1 vid1 vid1)" 
    by(auto simp add: p1_def dfree_Const)
  have osafe2:"osafe (OProd (OSing vid1 (f1 fid1 vid1)) (OSing vid2 (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1))))"
    by(auto simp add: f1_def expand_singleton osafe.intros dfree.intros vne12)
  note sem = ode_alt_sem[OF osafe fsafe]
  note sem2 = ode_alt_sem[OF osafe2 fsafe]
  have p2safe:"fsafe (p1 vid2 vid1)" by(auto simp add: p1_def dfree_Const)
  show "valid DGaxiom"
    apply(auto simp  del: prog_sem.simps(8) simp add: DGaxiom_def valid_def sem sem2)
     apply(rule exI[where x=0], auto simp add: f1_def p1_def expand_singleton)
     subgoal for I a b aa ba sol t
     proof -
       assume good_interp:"is_interp I"
       assume "
∀aa ba. (∃sol t. (aa, ba) = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t) ∧
                      0 ≤ t ∧
                      (sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
                       {x. Predicates I vid1
                            (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                   (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) x))} ∧
                      VSagree (sol 0) a {uu. uu = vid1 ∨
                            Inl uu ∈ Inl ` {x. ∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0)} ∨
                            (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}) ⟶
             Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (aa, ba))"
       then have 
         bigAll:"
⋀aa ba. (∃sol t. (aa, ba) = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t) ∧
                      0 ≤ t ∧
                      (sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
                       {x. Predicates I vid1
                            (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                   (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) x))} ∧
                      VSagree (sol 0) a {uu. uu = vid1 ∨ (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}) ⟶
             Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (aa, ba))"
         by (auto)
       assume aaba:"(aa, ba) =
  mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
           (OSing vid2
             (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
               ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
   (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t)"
       assume t:"0 ≤ t"
       assume sol:"
     (sol solves_ode
   (λa b. (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0) +
          (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) b else 0)))
   {0..t} {x. Predicates I vid1
               (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                      (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                                (OSing vid2
                                  (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                    ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                        (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) x))}"
     assume VSag:"VSagree (sol 0) (χ y. if vid2 = y then 0 else fst (a, b) $ y)
     {x. x = vid2 ∨ x = vid1 ∨ x = vid2 ∨ x = vid1 ∨ Inl x ∈ Inl ` {x. x = vid2 ∨ x = vid1} ∨ x = vid1}"
       let ?sol = "(λt. χ i. if i = vid1 then sol t $ vid1 else 0)"
       let ?aaba' = "mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (?sol t)"
     from bigAll[of "fst ?aaba'" "snd ?aaba'"] 
     have bigEx:"(∃sol t. ?aaba' = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t) ∧
                        0 ≤ t ∧
                        (sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
                         {x. Predicates I vid1
                              (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                     (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) x))} ∧
                        VSagree (sol 0) a {uu. uu = vid1 ∨ (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}) ⟶
               Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?aaba'))" 
       by simp
     have pre1:"?aaba' = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (?sol t)" 
       by (rule refl)
     have agreeL:"⋀s. fst (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                   (OSing vid2
                     (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                       ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
           (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol s)) $ vid1 = sol s $ vid1"
       subgoal for s
         using mk_v_agree[of I "(OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                   (OSing vid2
                      (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                        ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))" "(χ y. if vid2 = y then 0 else fst (a, b) $ y, b)" "(sol s)"]
         unfolding Vagree_def by auto done
       have agreeR:"⋀s. fst (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (χ i. if i = vid1 then sol s $ vid1 else 0)) $ vid1 = sol s $ vid1" 
         subgoal for s
           using mk_v_agree[of "I" "(OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))" "(a, b)" "(χ i. if i = vid1 then sol s $ vid1 else 0)"]
           unfolding Vagree_def by auto
         done
       have FV:"(FVF (p1 vid1 vid1)) = {Inl vid1}" unfolding p1_def expand_singleton
         apply auto subgoal for x xa apply(cases "xa = vid1") by auto done
       have agree:"⋀s. Vagree (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                     (OSing vid2
                       (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                         ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
             (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol s)) (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (χ i. if i = vid1 then sol s $ vid1 else 0)) (FVF (p1 vid1 vid1))"
         using agreeR agreeL unfolding Vagree_def FV by auto
       note con_sem_eq = coincidence_formula[OF fsafe Iagree_refl agree]
       have constraint:"⋀s. 0 ≤ s ∧ s ≤ t ⟹
         Predicates I vid1
         (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
               (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (χ i. if i = vid1 then sol s $ vid1 else 0)))"
         using sol apply simp
         apply(drule solves_odeD(2))
          apply auto[1]
         subgoal for s using con_sem_eq by (auto simp add: p1_def expand_singleton)
         done
       have eta:"sol = (λt. χ i. sol t $ i)" by (rule ext, rule vec_extensionality, simp)
       have yet_another_eq:"⋀x. (λxa. xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol x) else 0) +
                          (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol x) else 0)))
 = (λxa. (χ i. (xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol x) else 0) +
                          (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol x) else 0))) $ i))"
         subgoal for x by (rule ext, rule vec_extensionality, simp) done
       have sol_deriv:"⋀x. x ∈{0..t} ⟹
           (sol has_derivative
            (λxa. xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol x) else 0) +
                          (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol x) else 0))))
            (at x within {0..t})"
         using sol apply simp
         apply(drule solves_odeD(1))
         unfolding has_vderiv_on_def has_vector_derivative_def by auto
       then have sol_deriv:"⋀x. x ∈ {0..t} ⟹
           ((λt. χ i. sol t $ i) has_derivative
            (λxa. (χ i. (xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol x) else 0) +
                          (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol x) else 0))) $ i)))
            (at x within {0..t})" using yet_another_eq eta by auto
       have sol_deriv1: "⋀x. x ∈ {0..t} ⟹
          ((λt. sol t $ vid1) has_derivative
           (λxa. (xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol x) else 0) +
                         (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol x) else 0)) $ vid1)))
           (at x within {0..t})"
         subgoal for s
           (* I heard higher-order unification is hard.*)
         apply(rule has_derivative_proj[of "(λ i t. sol t $ i)" "(λj xa. (xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol s) else 0) +
                         (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (sol s) else 0)) $ j))" "at s within {0..t}""vid1"])
         using sol_deriv[of s] by auto done
      have hmm:"⋀s. (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (sol s)) = (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (χ i. if i = vid1 then sol s $ vid1 else 0))"
        by(rule vec_extensionality, auto)
      have aha:"⋀s. (λxa. xa * sterm_sem I (f1 fid1 vid1) (sol s)) = (λxa. xa * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0))"
        subgoal for s
          apply(rule ext)
          subgoal for xa using hmm by (auto simp add: f1_def) done done 
      let ?sol' = "(λs. (λxa. χ i. if i = vid1 then xa * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0) else 0))"
      let ?project_me_plz = "(λt. (χ i. if i = vid1 then ?sol t $ vid1 else 0))"
      have sol_deriv_eq:"⋀s. s ∈{0..t} ⟹
     ((λt. (χ i. if i = vid1 then ?sol t $ vid1 else 0)) has_derivative ?sol' s) (at s within {0..t})"
        subgoal for s
          apply(rule has_derivative_vec)
          subgoal for i
            apply (cases "i = vid1", cases "i = vid2", auto)
             using vne12 apply simp
            using sol_deriv1[of s] using aha by auto
          done done
      have yup:"(λt. (χ i. if i = vid1 then ?sol t $ vid1 else 0) $ vid1) = (λt. sol t $ vid1)"
        by(rule ext, auto)
      have maybe:"⋀s. (λxa. xa * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0)) = (λxa. (χ i. if i = vid1 then xa * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0) else 0) $ vid1) "
        by(rule ext, auto)
      have almost:"(λx. if vid1 = vid1 then (χ i. if i = vid1 then sol x $ vid1 else 0) $ vid1 else 0) =
(λx.  (χ i. if i = vid1 then sol x $ vid1 else 0) $ vid1)" by(rule ext, auto)
      have almost':"⋀s. (λh. if vid1 = vid1 then h * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0) else 0) = (λh. h * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0))"
        by(rule ext, auto)
      have deriv':" ⋀x. x ∈ {0..t} ⟹
     ((λt. χ i. if i = vid1 then sol t $ vid1 else 0) has_derivative
      (λxa. (χ i. xa *⇩R (if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol x $ vid1 else 0) else 0))))
      (at x within {0..t})"
        subgoal for s
          apply(rule has_derivative_vec)
          subgoal for i
            apply(cases "i = vid1")
             prefer 2 subgoal by auto
            apply auto              
            using has_derivative_proj[OF sol_deriv_eq[of s], of vid1] using  yup maybe[of s] almost almost'[of s] 
            by fastforce
          done 
        done
      have derEq:"⋀s. (λxa. (χ i. xa *⇩R (if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0) else 0)))
 = (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol s $ vid1 else 0) else 0))"
        subgoal for s apply (rule ext, rule vec_extensionality) by auto done
      have "⋀x. x ∈ {0..t} ⟹
     ((λt. χ i. if i = vid1 then sol t $ vid1 else 0) has_derivative
      (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol x $ vid1 else 0) else 0)))
      (at x within {0..t})" subgoal for s using deriv'[of s] derEq[of s] by auto done
      then have deriv:"((λt. χ i. if i = vid1 then sol t $ vid1 else 0) has_vderiv_on
        (λt. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid1 then sol t $ vid1 else 0) else 0))
        {0..t}"
        unfolding has_vderiv_on_def has_vector_derivative_def
        by auto 
      have pre2:"(?sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
     {x. Predicates I vid1
          (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                 (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) x))}"
        apply(rule solves_odeI)
         subgoal by (rule deriv)
        subgoal for s using constraint by auto
        done
      have pre3:"VSagree (?sol 0) a {u. u = vid1 ∨ (∃x. Inl u ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}"
        using vne12 VSag unfolding VSagree_def by simp 
      have bigPre:"(∃sol t. ?aaba' = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then Var vid1 else Const 0))) (a, b) (sol t) ∧
                      0 ≤ t ∧
                      (sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
                       {x. Predicates I vid1
                            (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                   (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then Var vid1 else Const 0))) (a, b) x))} ∧
                      VSagree (sol 0) a {u. u = vid1 ∨ (∃x. Inl u ∈ FVT (if x = vid1 then Var vid1 else Const 0))})"
        apply(rule exI[where x="?sol"])
        apply(rule exI[where x=t])
        apply(rule conjI)
         apply(rule pre1)
        apply(rule conjI)
         apply(rule t)
        apply(rule conjI)
         apply(rule pre2)
        by(rule pre3)
      have pred2:"Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) ?aaba')"
        using bigEx bigPre by auto
      then have pred2':"?aaba' ∈ fml_sem I (p1 vid2 vid1)" unfolding p1_def expand_singleton by auto
      let ?res_state = "(mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                    (OSing vid2
                      (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                        ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
            (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t))"
      have aabaX:"(fst ?aaba') $ vid1 = sol t $ vid1" 
        using aaba mk_v_agree[of "I" "(OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))"
 "(a, b)" "(?sol t)"] 
      proof -
        assume " Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (χ i. if i = vid1 then sol t $ vid1 else 0))
     (a, b) (- semBV I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))) ∧
   Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (χ i. if i = vid1 then sol t $ vid1 else 0))
     (mk_xode I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (χ i. if i = vid1 then sol t $ vid1 else 0))
     (semBV I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))))"
        then have ag:" Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (?sol t))
   (mk_xode I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (?sol t))
   (semBV I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))))"
          by auto
        have sembv:"(semBV I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))) = {Inl vid1, Inr vid1}"
          by auto
        have sub:"{Inl vid1} ⊆ {Inl vid1, Inr vid1}" by auto
        have ag':"Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (?sol t))
          (mk_xode I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (?sol t)) {Inl vid1}" 
          using ag agree_sub[OF sub] sembv by auto
        then have eq1:"fst (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (?sol t)) $ vid1 
          = fst (mk_xode I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (?sol t)) $ vid1" unfolding Vagree_def by auto
        moreover have "... = sol t $ vid1" by auto
        ultimately show ?thesis by auto
      qed
      have res_stateX:"(fst ?res_state) $ vid1 = sol t $ vid1" 
        using mk_v_agree[of I "(OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                    (OSing vid2
                      (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                        ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))"
            "(χ y. if vid2 = y then 0 else fst (a, b) $ y, b)" "(sol t)"]
      proof -
        assume "Vagree (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                     (OSing vid2
                       (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                         ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
             (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t))
     (χ y. if vid2 = y then 0 else fst (a, b) $ y, b)
     (- semBV I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))) ∧
    Vagree (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                     (OSing vid2
                       (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                         ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
             (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t))
     (mk_xode I
       (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
         (OSing vid2
           (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
             ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
       (sol t))
     (semBV I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                (OSing vid2
                  (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                    ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0))))))"
        then have ag:" Vagree (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                 (OSing vid2
                   (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                     ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
         (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t))
 (mk_xode I
   (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
     (OSing vid2
       (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
         ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
   (sol t))
 (semBV I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
            (OSing vid2
              (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0))))))" by auto
        have sembv:"(semBV I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
            (OSing vid2
              (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))) = {Inl vid1, Inr vid1, Inl vid2, Inr vid2}" by auto
        have sub:"{Inl vid1} ⊆ {Inl vid1, Inr vid1, Inl vid2, Inr vid2}" by auto
        have ag':"Vagree (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                 (OSing vid2
                   (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                     ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
         (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t))
   (mk_xode I
     (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
       (OSing vid2
         (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
           ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
     (sol t)) {Inl vid1}" using ag sembv agree_sub[OF sub] by auto
        then have "fst ?res_state $ vid1 = fst ((mk_xode I
     (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
       (OSing vid2
         (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
           ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
     (sol t))) $ vid1" unfolding Vagree_def by blast
        moreover have "... = sol t $ vid1" by auto
        ultimately show "?thesis" by linarith
      qed
     have agree:"Vagree ?aaba' (?res_state) (FVF (p1 vid2 vid1))"
       unfolding p1_def Vagree_def using aabaX res_stateX by auto
     have fml_sem_eq:"(?res_state ∈ fml_sem I (p1 vid2 vid1)) = (?aaba' ∈ fml_sem I (p1 vid2 vid1))"
       using coincidence_formula[OF p2safe Iagree_refl agree, of I] by auto
     then show "Predicates I vid2
     (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
            (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                      (OSing vid2
                        (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                          ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
              (χ y. if vid2 = y then 0 else fst (a, b) $ y, b) (sol t)))"
     using pred2 unfolding p1_def expand_singleton by auto
  qed
subgoal for I a b r aa ba sol t
proof -
  assume good_interp:"is_interp I"
  assume bigAll:"    ∀aa ba. (∃sol t. (aa, ba) =
                     mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                              (OSing vid2
                                (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                  ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                      (χ y. if vid2 = y then r else fst (a, b) $ y, b) (sol t) ∧
                     0 ≤ t ∧
                     (sol solves_ode
                      (λa b. (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0) +
                             (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) b else 0)))
                      {0..t} {x. Predicates I vid1
                                  (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                         (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                                                   (OSing vid2
                                                     (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                                       ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                                           (χ y. if vid2 = y then r else fst (a, b) $ y, b) x))} ∧
                     VSagree (sol 0) (χ y. if vid2 = y then r else fst (a, b) $ y)
                      {uu. uu = vid2 ∨
                            uu = vid1 ∨
                            uu = vid2 ∨
                            uu = vid1 ∨
                            Inl uu
                            ∈ Inl ` ({x. ∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0)} ∪
                                      {x. x = vid2 ∨ (∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0))}) ∨
                            (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}) ⟶
            Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (aa, ba))"
    assume aaba:"(aa, ba) = mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t)"
    assume t:"0 ≤ t"
    assume sol:"(sol solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t}
     {x. Predicates I vid1
          (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                 (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) x))}"
    assume VSA:"VSagree (sol 0) a
     {uu. uu = vid1 ∨
           Inl uu ∈ Inl ` {x. ∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0)} ∨
           (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))}"
    let ?xode = "(λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)"
    let ?xconstraint = UNIV
    let ?ivl = "ll_on_open.existence_ivl {0 .. t} ?xode ?xconstraint 0 (sol 0)"
    have freef1:"dfree ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
      by(auto simp add: dfree_Fun dfree_Const)
    have simple_term_inverse':"⋀θ. dfree θ ⟹ raw_term (simple_term θ) = θ"
      using simple_term_inverse by auto
    have old_lipschitz:"local_lipschitz (UNIV::real set) UNIV (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)"
      apply(rule c1_implies_local_lipschitz[where f'="(λ (t,b). blinfun_vec(λ i. if i = vid1 then blin_frechet (good_interp I) (simple_term (Function fid1 (λ i. if i = vid1 then Var vid1 else Const 0))) b else Blinfun(λ _. 0)))"])
         apply auto
       subgoal for x
         apply(rule has_derivative_vec)
         subgoal for i
           apply(auto simp add:  bounded_linear_Blinfun_apply good_interp_inverse good_interp)
           apply(auto simp add: simple_term_inverse'[OF freef1])
           apply(cases "i = vid1")
            apply(auto simp add: f1_def expand_singleton)
         proof -
           let ?h = "(λb. Functions I fid1 (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) b))"
           let ?h' = "(λb'. FunctionFrechet I fid1 (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) x) (χ i. frechet I (if i = vid1 then trm.Var vid1 else Const 0) x b'))" 
           let ?f = "(λ b. (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) b))"
           let ?f' = "(λ b'. (χ i. frechet I (if i = vid1 then trm.Var vid1 else Const 0) x b'))"
           let ?g = "Functions I fid1"
           let ?g'= "FunctionFrechet I fid1 (?f x)"
           have heq:"?h = ?g ∘ ?f" by(rule ext, auto)
           have heq':"?h' = ?g' ∘ ?f'" by(rule ext, auto)
           have fderiv:"(?f has_derivative ?f') (at x)"
             apply(rule has_derivative_vec)
             by (auto simp add: svar_deriv axis_def)
           have gderiv:"(?g has_derivative ?g') (at (?f x))"
             using good_interp unfolding is_interp_def by blast
           have gfderiv: "((?g ∘ ?f) has_derivative(?g' ∘ ?f')) (at x)"
             using fderiv gderiv diff_chain_at by blast
           have boring_eq:"(λb. Functions I fid1 (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) b)) =
             sterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))"
             by(rule ext, auto)
           have "(?h has_derivative ?h') (at x)" using gfderiv heq heq' by auto
           then show "(sterm_sem I ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)) has_derivative
 (λv'. (THE f'. ∀x. (Functions I fid1 has_derivative f' x) (at x)) (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) x)
        (χ i. frechet I (if i = vid1 then trm.Var vid1 else Const 0) x v')))
 (at x)"
             using boring_eq by auto
         qed
         done
    proof -
      have the_thing:"continuous_on (UNIV::('sz Rvec set)) 
        (λb.
          blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) b
                else Blinfun (λ_. 0)))"
         apply(rule continuous_blinfun_vec')
         subgoal for i
           apply(cases "i = vid1")
            apply(auto)
            using frechet_continuous[OF good_interp freef1] by (auto simp add: continuous_on_const)           
         done
       have another_cont:"continuous_on (UNIV) 
        (λx.
          blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (snd x)
                else Blinfun (λ_. 0)))"
         apply(rule continuous_on_compose2[of UNIV "(λb. blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) b
                else Blinfun (λ_. 0)))"])
           apply(rule the_thing)
          by (auto intro!: continuous_intros)
       have ext:"(λx. case x of
        (t, b) ⇒
          blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) b
                else Blinfun (λ_. 0))) =(λx.
          blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (snd x)
           else Blinfun (λ_. 0))) " apply(rule ext, auto) 
         by (metis snd_conv)
       then show  "continuous_on (UNIV) 
        (λx. case x of
        (t, b) ⇒
          blinfun_vec
           (λi. if i = vid1 then blin_frechet (good_interp I) (simple_term ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) b
                else Blinfun (λ_. 0)))"
         using another_cont
         by (simp add: another_cont local.ext)
    qed
    have old_continuous:" ⋀x. x ∈ UNIV ⟹ continuous_on UNIV (λt. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) x else 0)"
      by(rule continuous_on_const)
    interpret ll_old: ll_on_open_it "UNIV" ?xode ?xconstraint 0 
      apply(standard)
          subgoal by auto
         prefer 3 subgoal by auto
        prefer 3 subgoal by auto
       apply(rule old_lipschitz)
      by (rule old_continuous)
    let ?ivl = "(ll_old.existence_ivl 0 (sol 0))"
    let ?flow = "ll_old.flow 0 (sol 0)"
    have tclosed:"{0..t} = {0--t}" using t real_Icc_closed_segment by auto
    have "(sol  solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0..t} UNIV"
      apply(rule solves_ode_supset_range)
       apply(rule sol)
      by auto
    then have sol':"(sol  solves_ode (λa b. χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0)) {0--t} UNIV"
      using tclosed by auto
    have sub:"{0--t} ⊆ ll_old.existence_ivl 0 (sol 0)"
      apply(rule ll_old.closed_segment_subset_existence_ivl)
      apply(rule ll_old.existence_ivl_maximal_segment)
        apply(rule sol')
       apply(rule refl)
      by auto
    have usol_old:"(?flow  usolves_ode ?xode from 0) ?ivl UNIV"
      by(rule ll_old.flow_usolves_ode, auto)
    have sol_old:"(ll_old.flow 0 (sol 0) solves_ode ?xode) ?ivl UNIV"
      by(rule ll_old.flow_solves_ode, auto)
    have another_sub:"⋀s. s ∈ {0..t} ⟹ {s--0} ⊆ {0..t}"
      unfolding closed_segment_def
      apply auto
      by (metis diff_0_right diff_left_mono mult.commute mult_left_le order.trans)
    have sol_eq_flow:"⋀s. s ∈ {0..t} ⟹ sol s = ?flow s"
      using usol_old apply simp
      apply(drule usolves_odeD(4)) (* 7 subgoals*)
            apply auto
       subgoal for s x
       proof -
         assume xs0:"x ∈ {s--0}"
         assume s0:"0 ≤ s" and st: "s ≤ t"
         have "{s--0} ⊆ {0..t}" using another_sub[of s] s0 st by auto
         then have "x ∈ {0..t}" using xs0 by auto
         then have "x ∈ {0--t}" using tclosed by auto
         then show "x ∈ ll_old.existence_ivl 0 (sol 0)"
           using sub by auto
       qed
       apply(rule solves_ode_subset)
        using sol' apply auto[1]
       subgoal for s
       proof - 
         assume s0:"0 ≤ s" and st:"s ≤ t"
         show "{s--0} ⊆ {0--t}"
           using tclosed unfolding closed_segment using s0 st
           using another_sub intervalE by blast
       qed
      done
    have sol_deriv_orig:"⋀s. s∈?ivl ⟹  (?flow has_derivative (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0))) (at s within ?ivl)"
      using sol_old apply simp
      apply(drule solves_odeD(1))
      by (auto simp add: has_vderiv_on_def has_vector_derivative_def)
    have sol_eta:"(λt. χ i. ?flow t $ i) = ?flow" by(rule ext, rule vec_extensionality, auto)
    have sol_deriv_eq1:"⋀s i. (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)) = (λxa. χ i. xa * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0))"
      by(rule ext, rule vec_extensionality, auto)
    have sol_deriv_proj:"⋀s i. s∈?ivl ⟹  ((λt. ?flow t $ i) has_derivative (λxa. (xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)) $ i)) (at s within ?ivl)"         
      subgoal for s i
        apply(rule has_derivative_proj[of "(λ i t. ?flow t $ i)" "(λ i t'. (t' *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)) $ i)" "(at s within ?ivl)" "i"])
        using sol_deriv_orig[of s] sol_eta sol_deriv_eq1 by auto
      done
    have sol_deriv_eq2:"⋀s i. (λxa. xa * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)) = (λxa. (xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)) $ i)"
      by(rule ext, auto)
    have sol_deriv_proj':"⋀s i. s∈?ivl ⟹  ((λt. ?flow t $ i) has_derivative (λxa. xa * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0))) (at s within ?ivl)"
      subgoal for s i using sol_deriv_proj[of s i] sol_deriv_eq2[of i s] by metis done  
    have sol_deriv_proj_vid1:"⋀s. s∈?ivl ⟹  ((λt. ?flow t $ vid1) has_derivative (λxa. xa * (sterm_sem I (f1 fid1 vid1) (?flow s)))) (at s within ?ivl)"
      subgoal for s
        using sol_deriv_proj'[of s vid1] by auto done
    have deriv1_args:"⋀s. s ∈ ?ivl ⟹ ((λ t. (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?flow t))) has_derivative ((λ t'. χ i . t' * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)))) (at s within ?ivl)"
      apply(rule has_derivative_vec)
      by (auto simp add: sol_deriv_proj_vid1)          
    have con_fid:"⋀fid. continuous_on ?ivl (λx. sterm_sem I (f1 fid vid1) (?flow x))"
      subgoal for fid
      apply(rule has_derivative_continuous_on[of "?ivl" "(λx. sterm_sem I (f1 fid vid1) (?flow x))"
          "(λt t'.  FunctionFrechet I fid (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?flow t)) (χ i . t' * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow t) else 0)))"])
    proof -
      fix s
      assume ivl:"s ∈ ?ivl"
      let ?h = "(λx. sterm_sem I (f1 fid vid1) (?flow x))"
      let ?g = "Functions I fid"
      let ?f = "(λx. (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?flow x)))"
      let ?h' = "(λt'. FunctionFrechet I fid (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?flow s))
              (χ i. t' * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0)))"
      let ?g' = "FunctionFrechet I fid (?f s)"
      let ?f' = "(λ t'. χ i . t' * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0))"
      have heq:"?h = ?g ∘ ?f" unfolding comp_def f1_def expand_singleton by auto
      have heq':"?h' = ?g' ∘ ?f'" unfolding comp_def by auto
      have fderiv:"(?f has_derivative ?f') (at s within ?ivl)"
        using deriv1_args[OF ivl] by auto
      have gderiv:"(?g has_derivative ?g') (at (?f s) within (?f ` ?ivl))"
        using good_interp unfolding is_interp_def 
        using  has_derivative_subset by blast
      have gfderiv:"((?g ∘ ?f) has_derivative (?g' ∘ ?f')) (at s within ?ivl)"
        using fderiv gderiv diff_chain_within by blast
      show "((λx. sterm_sem I (f1 fid vid1) (?flow x)) has_derivative
       (λt'. FunctionFrechet I fid (χ i. sterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (?flow s))
              (χ i. t' * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (?flow s) else 0))))
       (at s within ?ivl)"
        using heq heq' gfderiv by auto
    qed
    done
    have con:"⋀x. continuous_on (?ivl) (λt. x * sterm_sem I (f1 fid2 vid1) (?flow t) + sterm_sem I (f1 fid3 vid1) (?flow t))"
      apply(rule continuous_on_add)
       apply(rule continuous_on_mult_left)
       apply(rule con_fid[of fid2])
      by(rule con_fid[of fid3])
    let ?axis = "(λ i. Blinfun(axis i))"
    have bounded_linear_deriv:"⋀t. bounded_linear (λy' . y' *⇩R  sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t))" 
      using bounded_linear_scaleR_left by blast
    have ll:"local_lipschitz (ll_old.existence_ivl 0 (sol 0)) UNIV (λt y. y * sterm_sem I (f1 fid2 vid1) (?flow t) + sterm_sem I (f1 fid3 vid1) (?flow t))"
      apply(rule c1_implies_local_lipschitz[where f'="(λ (t,y). Blinfun(λy' . y' *⇩R  sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t)))"])
         apply auto
       subgoal for t x
         apply(rule has_derivative_add_const)
         proof -
           have deriv:"((λx. x * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t)) has_derivative (λx. x * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t))) (at x)"
             by(auto intro: derivative_eq_intros)
           have eq:"(λx. x * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t)) = blinfun_apply (Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t)))"
             apply(rule ext)
             using bounded_linear_deriv[of t]  by (auto simp add:  bounded_linear_Blinfun_apply)
           show "((λx. x * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t)) has_derivative
              blinfun_apply (Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t))))
              (at x)" using deriv eq by auto
         qed
      apply(auto intro: continuous_intros simp add: split_beta')
    proof -
      have bounded_linear:"⋀x. bounded_linear (λy'. y' * sterm_sem I (f1 fid2 vid1) x)" 
        by (simp add: bounded_linear_mult_left)
      have eq:"(λx. Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) x)) = (λx. (sterm_sem I (f1 fid2 vid1) x) *⇩R id_blinfun)"
        apply(rule ext, rule blinfun_eqI)
        subgoal for x i
          using bounded_linear[of x] apply(auto simp add: bounded_linear_Blinfun_apply)
          by (simp add: blinfun.scaleR_left)
        done
      have conFlow:"continuous_on (ll_old.existence_ivl 0 (sol 0)) (ll_old.flow 0 (sol 0))"
        using ll_old.general.flow_continuous_on by blast
      have conF':"continuous_on (ll_old.flow 0 (sol 0) ` ll_old.existence_ivl 0 (sol 0)) 
            (λx. (sterm_sem I (f1 fid2 vid1) x) *⇩R id_blinfun)"
        apply(rule continuous_on_scaleR)
         apply(auto intro: continuous_intros)
        apply(rule sterm_continuous')
         apply(rule good_interp)
        by(auto simp add: f1_def intro: dfree.intros) 
      have conF:"continuous_on (ll_old.flow 0 (sol 0) ` ll_old.existence_ivl 0 (sol 0)) 
            (λx. Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) x))"
        apply(rule continuous_on_compose2[of "UNIV" "(λx. Blinfun (λy'. y' * x))" "(ll_old.flow 0 (sol 0) ` ll_old.existence_ivl 0 (sol 0))" "sterm_sem I (f1 fid2 vid1)"]) 
          subgoal by (metis blinfun_mult_left.abs_eq bounded_linear_blinfun_mult_left continuous_on_eq linear_continuous_on)
         apply(rule sterm_continuous')
          apply(rule good_interp)
        by(auto simp add: f1_def intro: dfree.intros) 
      show "continuous_on (ll_old.existence_ivl 0 (sol 0) × UNIV) (λx. Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) (fst x))))"
        apply(rule continuous_on_compose2[of "ll_old.existence_ivl 0 (sol 0)" "(λx. Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) x)))" "(ll_old.existence_ivl 0 (sol 0) × UNIV)" "fst"])
          apply(rule continuous_on_compose2[of "(ll_old.flow 0 (sol 0) ` ll_old.existence_ivl 0 (sol 0))" "(λx. Blinfun (λy'. y' * sterm_sem I (f1 fid2 vid1) x))" 
                "(ll_old.existence_ivl 0 (sol 0))" "(ll_old.flow 0 (sol 0))"])
            using conF conFlow by (auto intro!: continuous_intros)
      qed
    let ?ivl = "ll_old.existence_ivl 0 (sol 0)"
    ― ‹Construct solution to ODE for ‹y'› here:›
    let ?yode = "(λt y. y * sterm_sem I (f1 fid2 vid1) (?flow t) + sterm_sem I (f1 fid3 vid1) (?flow t))"
    let ?ysol0 = r
    interpret ll_new: ll_on_open_it "?ivl" "?yode" "UNIV" 0
      apply(standard)
          apply(auto)
       apply(rule ll)
      by(rule con)
    have sol_new:"(ll_new.flow 0 r solves_ode ?yode) (ll_new.existence_ivl 0 r) UNIV"
      by(rule ll_new.flow_solves_ode, auto)
    have more_lipschitz:"⋀tm tM. tm ∈ ll_old.existence_ivl 0 (sol 0) ⟹
         tM ∈ ll_old.existence_ivl 0 (sol 0) ⟹
         ∃M L. ∀t∈{tm..tM}. ∀x. ¦x * sterm_sem I (f1 fid2 vid1) (?flow t) + sterm_sem I (f1 fid3 vid1) (?flow t)¦ ≤ M + L * ¦x¦"
    proof -
      fix tm tM
      assume tm:"tm ∈ ll_old.existence_ivl 0 (sol 0)"
      assume tM:"tM ∈ ll_old.existence_ivl 0 (sol 0)"
      let ?f2 = "(λt. sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) t))"
      let ?f3 = "(λt. sterm_sem I (f1 fid3 vid1) (ll_old.flow 0 (sol 0) t))"
      let ?boundLP = "(λL t . (tm ≤ t ∧ t ≤ tM ⟶ ¦?f2 t¦ ≤ L))"
      let ?boundL = "(SOME L. (∀t. ?boundLP L t))"
      have compactT:"compact {tm..tM}" by auto
      have sub:"{tm..tM} ⊆ ll_old.existence_ivl 0 (sol 0)"
        by (metis atLeastatMost_empty_iff empty_subsetI ll_old.general.segment_subset_existence_ivl real_Icc_closed_segment tM tm)
      let ?f2abs = "(λx. abs(?f2 x))"
      have neg_compact:"⋀S::real set. compact S ⟹ compact ((λx. -x) ` S)"
        by(rule compact_continuous_image, auto intro: continuous_intros)
      have compactf2:"compact (?f2 ` {tm..tM})"
        apply(rule compact_continuous_image)
         apply(rule continuous_on_compose2[of UNIV "sterm_sem I (f1 fid2 vid1)" "{tm..tM}" "ll_old.flow 0 (sol 0)"])
           apply(rule sterm_continuous)
            apply(rule good_interp)
           subgoal by (auto intro: dfree.intros simp add: f1_def)
          apply(rule continuous_on_subset)
           prefer 2 apply (rule sub)
          subgoal using ll_old.general.flow_continuous_on by blast
         by auto
      then have boundedf2:"bounded (?f2 ` {tm..tM})" using compact_imp_bounded by auto
      then have boundedf2neg:"bounded ((λx. -x) ` ?f2 ` {tm..tM})" using compact_imp_bounded neg_compact by auto
      then have bdd_above_f2neg:"bdd_above ((λx. -x) ` ?f2 ` {tm..tM})" by (rule bounded_imp_bdd_above)
      then have bdd_above_f2:"bdd_above ( ?f2 ` {tm..tM})" using bounded_imp_bdd_above boundedf2 by auto
      have bdd_above_f2_abs:"bdd_above (abs ` ?f2 ` {tm..tM})" 
        using bdd_above_f2neg bdd_above_f2 unfolding bdd_above_def
        apply auto
        subgoal for M1 M2
          apply(rule exI[where x="max M1 M2"])
          by fastforce
        done
      then have theBound:"∃L. (∀t. ?boundLP L t)" 
        unfolding bdd_above_def norm_conv_dist 
        by (auto simp add: Ball_def Bex_def norm_conv_dist image_iff norm_bcontfun_def dist_blinfun_def)
      then have boundLP:"∀t. ?boundLP (?boundL) t" using someI[of "(λ L. ∀t. ?boundLP L t)"] by blast
      let ?boundMP = "(λM t. (tm ≤ t ∧ t ≤ tM ⟶ ¦?f3 t¦ ≤ M))"
      let ?boundM = "(SOME M. (∀t. ?boundMP M t))"
      have compactf3:"compact (?f3 ` {tm..tM})"
        apply(rule compact_continuous_image)
         apply(rule continuous_on_compose2[of UNIV "sterm_sem I (f1 fid3 vid1)" "{tm..tM}" "ll_old.flow 0 (sol 0)"])
           apply(rule sterm_continuous)
            apply(rule good_interp)
           subgoal by (auto intro: dfree.intros simp add: f1_def)
          apply(rule continuous_on_subset)
           prefer 2 apply (rule sub)
          subgoal using ll_old.general.flow_continuous_on by blast
         by auto
      then have boundedf3:"bounded (?f3 ` {tm..tM})" using compact_imp_bounded by auto
      then have boundedf3neg:"bounded ((λx. -x) ` ?f3 ` {tm..tM})" using compact_imp_bounded neg_compact by auto
      then have bdd_above_f3neg:"bdd_above ((λx. -x) ` ?f3 ` {tm..tM})" by (rule bounded_imp_bdd_above)
      then have bdd_above_f3:"bdd_above ( ?f3 ` {tm..tM})" using bounded_imp_bdd_above boundedf3 by auto
      have bdd_above_f3_abs:"bdd_above (abs ` ?f3 ` {tm..tM})" 
        using bdd_above_f3neg bdd_above_f3 unfolding bdd_above_def
        apply auto
        subgoal for M1 M2
          apply(rule exI[where x="max M1 M2"])
          by fastforce
        done
      then have theBound:"∃L. (∀t. ?boundMP L t)"
        unfolding bdd_above_def norm_conv_dist
        by (auto simp add: Ball_def Bex_def norm_conv_dist image_iff norm_bcontfun_def dist_blinfun_def)
      then have boundMP:"∀t. ?boundMP (?boundM) t" using someI[of "(λ M. ∀t. ?boundMP M t)"] by blast
      show "∃M L. ∀t∈{tm..tM}. ∀x. ¦x * ?f2 t + ?f3 t¦ ≤ M + L * ¦x¦"
        apply(rule exI[where x="?boundM"])
        apply(rule exI[where x="?boundL"])
        apply auto
      proof -
        fix t and x :: real
        assume ttm:"tm ≤ t"
        assume ttM:"t ≤ tM"
        from ttm ttM have ttmM:"tm ≤ t ∧ t ≤ tM" by auto 
        have leqf3:"¦?f3 t¦ ≤ ?boundM" using boundMP ttmM by auto
        have leqf2:"¦?f2 t¦ ≤ ?boundL" using boundLP ttmM by auto
        have gr0:" ¦x¦ ≥ 0" by auto
        have leqf2x:"¦?f2 t¦ * ¦x¦ ≤ ?boundL * ¦x¦" using gr0 leqf2
          by (metis (no_types, lifting) real_scaleR_def scaleR_right_mono)
        have "¦x * ?f2 t + ?f3 t¦ ≤ ¦x¦ * ¦?f2 t¦ + ¦?f3 t¦"
          proof -
            have f1: "⋀r ra. ¦r::real¦ * ¦ra¦ = ¦r * ra¦"
              by (metis norm_scaleR real_norm_def real_scaleR_def)
            have "⋀r ra. ¦(r::real) + ra¦ ≤ ¦r¦ + ¦ra¦"
              by (metis norm_triangle_ineq real_norm_def)
              then show ?thesis
              using f1 by presburger
          qed
        moreover have "... = ¦?f3 t¦ + ¦?f2 t¦ * ¦x¦"
          by auto
        moreover have "... ≤ ?boundM + ¦?f2 t¦ * ¦x¦"
          using leqf3 by linarith
        moreover have "... ≤ ?boundM + ?boundL * ¦x¦"
          using leqf2x  by linarith
        ultimately show "¦x * ?f2 t + ?f3 t¦ ≤ ?boundM + ?boundL * ¦x¦"
          by linarith
      qed
    qed
    have ivls_eq:"(ll_new.existence_ivl 0 r) = (ll_old.existence_ivl 0 (sol 0))"
      apply(rule ll_new.existence_ivl_eq_domain)
          apply auto
      apply (rule more_lipschitz)
      by auto
    have sub':"{0--t} ⊆ ll_new.existence_ivl 0 r"
      using sub ivls_eq by auto
    have sol_new':"(ll_new.flow 0 r solves_ode ?yode) {0--t} UNIV"
      by(rule solves_ode_subset, rule sol_new, rule sub')
    let ?soly = "ll_new.flow 0 r"
    let ?sol' = "(λt. χ i. if i = vid2 then ?soly t else sol t $ i)"
    let ?aaba' = "mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                             (OSing vid2
                               (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                 ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                         (χ y. if vid2 = y then r else fst (a, b) $ y, b)
                         (?sol' t)"
    have duh:"(fst ?aaba', snd ?aaba') = ?aaba'" by auto
    note bigEx = spec[OF spec[OF bigAll, where x="fst ?aaba'"], where x="snd ?aaba'"]
    have sol_deriv:"⋀s. s ∈ {0..t} ⟹ (sol has_derivative (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol s) else 0))) (at s within {0..t})"
       using sol apply simp
       by(drule solves_odeD(1), auto simp add: has_vderiv_on_def has_vector_derivative_def)
     have silly_eq1:"(λt. χ i. sol t $ i) = sol"
       by(rule ext, rule vec_extensionality, auto)
     have silly_eq2:"⋀s. (λxa. χ i. (xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol s) else 0)) $ i) = (λxa. xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol s) else 0))"
       by(rule ext, rule vec_extensionality, auto)
     have sol_proj_deriv:"⋀s i. s ∈ {0..t} ⟹ ((λ t. sol t $ i) has_derivative (λxa. (xa *⇩R (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (sol s) else 0)) $ i)) (at s within {0..t})"
       subgoal for s i
         apply(rule has_derivative_proj)
         using sol_deriv[of s] silly_eq1 silly_eq2[of s] by auto
       done
     have sol_proj_deriv_vid1:"⋀s. s ∈ {0..t} ⟹ ((λ t. sol t $ vid1) has_derivative (λxa. xa * sterm_sem I (f1 fid1 vid1) (sol s))) (at s within {0..t})"
       subgoal for s using sol_proj_deriv[of s vid1] by auto done
     have sol_proj_deriv_other:"⋀s i. s ∈ {0..t} ⟹ i ≠ vid1 ⟹ ((λ t. sol t $ i) has_derivative (λxa. 0)) (at s within {0..t})"
       subgoal for s i using sol_proj_deriv[of s i] by auto done
     have fact:"⋀x. x ∈{0..t} ⟹
   (ll_new.flow 0 r has_derivative
    (λxa. xa *⇩R (ll_new.flow 0 r x * sterm_sem I (f1 fid2 vid1) (ll_old.flow 0 (sol 0) x) +
                  sterm_sem I (f1 fid3 vid1) (ll_old.flow 0 (sol 0) x))))
    (at x within {0 .. t})"
       using sol_new' apply simp
       apply(drule solves_odeD(1))
       using tclosed unfolding has_vderiv_on_def has_vector_derivative_def by auto
     have new_sol_deriv:"⋀s. s ∈ {0..t} ⟹ (ll_new.flow 0 r has_derivative
      (λxa. xa *⇩R (ll_new.flow 0 r s * sterm_sem I (f1 fid2 vid1) (sol s) + sterm_sem I (f1 fid3 vid1) (sol s))))
      (at s within {0.. t})"
       subgoal for s
         using fact[of s] tclosed sol_eq_flow[of s] by auto
       done
     have sterm_agree:"⋀s. Vagree (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i, undefined) (sol s, undefined) {Inl vid1}"
       subgoal for s unfolding Vagree_def using vne12 by auto done
     have FVF:"(FVT (f1 fid2 vid1)) = {Inl vid1}" unfolding f1_def expand_singleton apply auto subgoal for x xa by (cases "xa = vid1", auto) done
     have FVF2:"(FVT (f1 fid3 vid1)) = {Inl vid1}" unfolding f1_def expand_singleton apply auto subgoal for x xa by (cases "xa = vid1", auto) done
     have sterm_agree_FVF:"⋀s. Vagree (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i, undefined) (sol s, undefined) (FVT (f1 fid2 vid1))"
       using sterm_agree FVF by auto
     have sterm_agree_FVF2:"⋀s. Vagree (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i, undefined) (sol s, undefined) (FVT (f1 fid3 vid1))"
       using sterm_agree FVF2 by auto
     have y_component_sem_eq2:"⋀s. sterm_sem I (f1 fid2 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)
        = sterm_sem I (f1 fid2 vid1) (sol s)"
       using coincidence_sterm[OF sterm_agree_FVF, of I] by auto
     have y_component_sem_eq3:"⋀s. sterm_sem I (f1 fid3 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)
        = sterm_sem I (f1 fid3 vid1) (sol s)"
       using coincidence_sterm[OF sterm_agree_FVF2, of I] by auto
     have y_component_ode_eq:"⋀s. s ∈ {0..t} ⟹ 
       (λxa. xa * (ll_new.flow 0 r s * sterm_sem I (f1 fid2 vid1) (sol s) + sterm_sem I (f1 fid3 vid1) (sol s)))
     = (λxa. xa * (sterm_sem I (f1 fid2 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) * ll_new.flow 0 r s +
             sterm_sem I (f1 fid3 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)))"
       subgoal for s
         apply(rule ext)
         subgoal for xa
           using y_component_sem_eq2 y_component_sem_eq3 by auto
         done
       done
     have agree_vid1:"⋀s. Vagree (sol s, undefined) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i, undefined) {Inl vid1}"
       unfolding Vagree_def using vne12 by auto
     have FVT_vid1:"FVT(f1 fid1 vid1) = {Inl vid1}" apply(auto simp add: f1_def) subgoal for x xa apply(cases "xa = vid1") by auto done
     have agree_vid1_FVT:"⋀s. Vagree (sol s, undefined) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i, undefined) (FVT (f1 fid1 vid1))"
       using FVT_vid1 agree_vid1 by auto
     have sterm_eq_vid1:"⋀s. sterm_sem I (f1 fid1 vid1) (sol s) = sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)"
       subgoal for  s
         using coincidence_sterm[OF agree_vid1_FVT[of s], of I] by auto
       done
     have vid1_deriv_eq:"⋀s. (λxa. xa * sterm_sem I (f1 fid1 vid1) (sol s)) =
       (λxa. xa * sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i))"
       subgoal for s
         apply(rule ext)
         subgoal for x'
           using sterm_eq_vid1[of s] by auto
         done done
     have inner_deriv:"⋀s. s ∈ {0..t} ⟹
   ((λt. χ i. if i = vid2 then ll_new.flow 0 r t else sol t $ i) has_derivative (λxa. (χ i. xa * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else
                                         if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else 0))))
                                         (at s within {0..t})"
       subgoal for s
         apply(rule has_derivative_vec)
         subgoal for i
           apply(cases "i = vid2")
           subgoal
             using vne12
             using new_sol_deriv[of s]
             using y_component_ode_eq by auto
           subgoal 
             apply(cases "i = vid1")
             using sol_proj_deriv_vid1[of s] vid1_deriv_eq[of s] sol_proj_deriv_other[of s i] by auto
           done
         done
       done
     have deriv_eta:"⋀s. (λxa. xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else 0) +
               (χ i. if i = vid2
                     then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1))
                           (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)
                     else 0)))
                     = (λxa. (χ i. xa * (if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else
                                         if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else 0))) "
       subgoal for s
         apply(rule ext)
         apply(rule vec_extensionality)
         using vne12 by auto
       done
     have sol'_deriv:"⋀s. s ∈ {0..t} ⟹
   ((λt. χ i. if i = vid2 then ll_new.flow 0 r t else sol t $ i) has_derivative
    (λxa. xa *⇩R ((χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i) else 0) +
                  (χ i. if i = vid2
                        then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1))
                              (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)
                        else 0))))
    (at s within {0..t})"
       subgoal for s
         using inner_deriv[of s] deriv_eta[of s] by auto done
     have FVT:"⋀i. FVT (if i = vid1 then trm.Var vid1 else Const 0) ⊆ {Inl vid1}" by auto
     have agree:"⋀s. Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol s)) (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
          (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)) {Inl vid1}"
       subgoal for s
         using mk_v_agree [of "I" "(OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))" "(a, b)" "(sol s)"]
         using mk_v_agree [of I "(OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))" "(χ y. if vid2 = y then r else fst (a, b) $ y, b)" "(χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)"]
         unfolding Vagree_def using vne12 by simp
       done
     have agree':"⋀s i. Vagree (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol s)) (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
          (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)) (FVT (if i = vid1 then trm.Var vid1 else Const 0))"
       subgoal for s i using agree_sub[OF FVT[of i] agree[of s]] by auto done
     have safe:"⋀i. dsafe (if i = vid1 then trm.Var vid1 else Const 0)" subgoal for i apply(cases "i = vid1", auto) done done           
     have dterm_sem_eq:"⋀s i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol s)) 
       = dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
       (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
          (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i))"
       subgoal for s i using coincidence_dterm[OF safe[of i] agree'[of s i], of I] by auto done
     have dterm_vec_eq:"⋀s. (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol s)))
       = (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
       (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
          (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)))"
       subgoal for s
         apply(rule vec_extensionality)
         subgoal for i using dterm_sem_eq[of i s] by auto
         done done
     have pred_same:"⋀s. s ∈ {0..t} ⟹ Predicates I vid1
        (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
               (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol s))) ⟹
Predicates I vid1
 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
        (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                  (OSing vid2
                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
          (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)))"
       subgoal for s using dterm_vec_eq[of s] by auto done
   have sol'_domain:"⋀s. 0 ≤ s ⟹
  s ≤ t ⟹
  Predicates I vid1
   (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
          (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                    (OSing vid2
                      (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                        ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                        (χ y. if vid2 = y then r else fst (a, b) $ y, b) (χ i. if i = vid2 then ll_new.flow 0 r s else sol s $ i)))"
       subgoal for s
         using sol apply simp
         apply(drule solves_odeD(2))
         using pred_same[of s] by auto
       done
     have sol':"(?sol' solves_ode
 (λa b. (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0) +
        (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) b else 0)))
 {0..t} {x. Predicates I vid1
             (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                    (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                              (OSing vid2
                                (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                  ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                      (χ y. if vid2 = y then r else fst (a, b) $ y, b) x))}"
       apply(rule solves_odeI)
       subgoal
         unfolding has_vderiv_on_def has_vector_derivative_def
         using sol'_deriv by auto
       by(auto, rule sol'_domain, auto)
     have set_eq:"{y. y = vid2 ∨ y = vid1 ∨ y = vid2 ∨ y = vid1 ∨ (∃x. Inl y ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))} = {vid1, vid2}"
       by auto
     have "VSagree (?sol' 0) (χ y. if vid2 = y then r else fst (a, b) $ y) {vid1, vid2}"
       using VSA unfolding VSagree_def by simp 
     then have VSA':" VSagree (?sol' 0) (χ y. if vid2 = y then r else fst (a, b) $ y)
       
 {y. y = vid2 ∨ y = vid1 ∨ y = vid2 ∨ y = vid1 ∨ (∃x. Inl y ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))} "
       by (auto simp add: set_eq)
     have bigPre:"(∃sol t. (fst ?aaba', snd ?aaba') =
                    mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                             (OSing vid2
                               (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                 ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                     ((χ y. if vid2 = y then r else fst (a,b) $ y), b) (sol t) ∧
                    0 ≤ t ∧
                    (sol solves_ode
                     (λa b. (χ i. if i = vid1 then sterm_sem I (f1 fid1 vid1) b else 0) +
                            (χ i. if i = vid2 then sterm_sem I (Plus (Times (f1 fid2 vid1) (trm.Var vid2)) (f1 fid3 vid1)) b else 0)))
                     {0..t} {x. Predicates I vid1
                                 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
                                        (mk_v I (OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                                                  (OSing vid2
                                                    (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                                                      ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))
                                          ((χ y. if vid2 = y then r else (fst (a,b)) $ y), b) x))} ∧
                    VSagree (sol 0) (χ y. if vid2 = y then r else fst (a,b) $ y)
                     {uu. uu = vid2 ∨
                    uu = vid1 ∨
                    uu = vid2 ∨
                    uu = vid1 ∨
                    Inl uu ∈ Inl ` ({x. ∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0)} ∪
                                     {x. x = vid2 ∨ (∃xa. Inl x ∈ FVT (if xa = vid1 then trm.Var vid1 else Const 0))}) ∨
                    (∃x. Inl uu ∈ FVT (if x = vid1 then trm.Var vid1 else Const 0))})"
       apply(rule exI[where x="?sol'"])
       apply(rule exI[where x=t])
       apply(rule conjI)
        subgoal by simp
       apply(rule conjI)
        subgoal by (rule t)
       apply(rule conjI)
        apply(rule sol')
        using VSA' unfolding VSagree_def by auto
     have pred_sem:"Predicates I vid2 (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) ?aaba')"
       using mp[OF bigEx bigPre] by auto
     let ?other_state = "(mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t))"
     have agree:"Vagree (?aaba') (?other_state) {Inl vid1} "
       using mk_v_agree [of "I" "(OProd (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))
                 (OSing vid2
                   (Plus (Times ($f fid2 (λi. if i = vid1 then trm.Var vid1 else Const 0)) (trm.Var vid2))
                     ($f fid3 (λi. if i = vid1 then trm.Var vid1 else Const 0)))))"
         "(χ y. if vid2 = y then r else fst (a, b) $ y, b)" "(?sol' t)"]
       using mk_v_agree [of "I" "(OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0)))" "(a, b)" "(sol t)"]
       unfolding Vagree_def using vne12 by simp
     have sub:"⋀i. FVT (if i = vid1 then trm.Var vid1 else Const 0) ⊆ {Inl vid1}"
       by auto
     have agree':"⋀i. Vagree (?aaba') (?other_state) (FVT (if i = vid1 then trm.Var vid1 else Const 0)) "
       subgoal for i using agree_sub[OF sub[of i] agree] by auto done
     have silly_safe:"⋀i. dsafe (if i = vid1 then trm.Var vid1 else Const 0)"
       subgoal for i
         apply(cases "i = vid1")
          by (auto simp add: dsafe_Var dsafe_Const)
       done
     have dsem_eq:"(χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) ?aaba')  = 
        (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0) ?other_state)"
       apply(rule vec_extensionality)
       subgoal for i
         using coincidence_dterm[OF silly_safe[of i] agree'[of i], of I] by auto
       done
     show
    "Predicates I vid2
     (χ i. dterm_sem I (if i = vid1 then trm.Var vid1 else Const 0)
            (mk_v I (OSing vid1 ($f fid1 (λi. if i = vid1 then trm.Var vid1 else Const 0))) (a, b) (sol t)))"
     using pred_sem dsem_eq by auto
 qed


done
qed
end end