l3lab/ntp-mathlib huggingface dataset:
private theorem Cofix.bisim_aux {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop) (h' : ∀ x, r x x)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  intro x
  rcases x; clear x; rename M (P F) α => x;
  intro y
  rcases y; clear y; rename M (P F) α => y;
  intro rxy
  apply Quot.sound
  let r' := fun x y => r (Quot.mk _ x) (Quot.mk _ y)
  have hr' : r' = fun x y => r (Quot.mk _ x) (Quot.mk _ y) := rfl
  have : IsPrecongr r' := by
    intro a b r'ab
    have h₀ :
      appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P a) =
        appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P b) :=
      by rw [appendFun_comp_id, comp_map, comp_map]; exact h _ _ r'ab
    have h₁ : ∀ u v : q.P.M α, Mcongr u v → Quot.mk r' u = Quot.mk r' v := by
      intro u v cuv
      apply Quot.sound
      dsimp [hr']
      rw [Quot.sound cuv]
      apply h'
    let f : Quot r → Quot r' :=
      Quot.lift (Quot.lift (Quot.mk r') h₁)
        (by
          intro c
          apply Quot.inductionOn
            (motive := fun c =>
              ∀b, r c b → Quot.lift (Quot.mk r') h₁ c = Quot.lift (Quot.mk r') h₁ b) c
          clear c
          intro c d
          apply Quot.inductionOn
            (motive := fun d => r (Quot.mk Mcongr c) d →
              Quot.lift (Quot.mk r') h₁ (Quot.mk Mcongr c) = Quot.lift (Quot.mk r') h₁ d) d
          clear d
          intro d rcd; apply Quot.sound; apply rcd)
    

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h' : ∀ (x : Cofix F α), r x x
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
x y : M (P F) α
rxy : r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
r' : M (P F) α → M (P F) α → Prop := fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
hr' : r' = fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
a b : M (P F) α
r'ab : r' a b
h₀ :
  (TypeVec.id ::: Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest (P F) a) =
    (TypeVec.id ::: Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest (P F) b)
h₁ : ∀ (u v : M (P F) α), Mcongr u v → Quot.mk r' u = Quot.mk r' v
f : Quot r → Quot r' :=
  Quot.lift (Quot.lift (Quot.mk r') h₁)
    (_ : ∀ (c b : Cofix F α), r c b → Quot.lift (Quot.mk r') h₁ c = Quot.lift (Quot.mk r') h₁ b)
⊢ MvQPF.abs ((TypeVec.id ::: Quot.mk r') <$$> M.dest (P F) a) =
    MvQPF.abs ((TypeVec.id ::: Quot.mk r') <$$> M.dest (P F) b)

Next tactic:
have : f ∘ Quot.mk r ∘ Quot.mk Mcongr = Quot.mk r' := rfl
private theorem Cofix.bisim_aux {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop) (h' : ∀ x, r x x)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  intro x
  rcases x; clear x; rename M (P F) α => x;
  intro y
  rcases y; clear y; rename M (P F) α => y;
  intro rxy
  apply Quot.sound
  let r' := fun x y => r (Quot.mk _ x) (Quot.mk _ y)
  have hr' : r' = fun x y => r (Quot.mk _ x) (Quot.mk _ y) := rfl
  have : IsPrecongr r' := by
    intro a b r'ab
    have h₀ :
      appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P a) =
        appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P b) :=
      by rw [appendFun_comp_id, comp_map, comp_map]; exact h _ _ r'ab
    have h₁ : ∀ u v : q.P.M α, Mcongr u v → Quot.mk r' u = Quot.mk r' v := by
      intro u v cuv
      apply Quot.sound
      dsimp [hr']
      rw [Quot.sound cuv]
      apply h'
    let f : Quot r → Quot r' :=
      Quot.lift (Quot.lift (Quot.mk r') h₁)
        (by
          intro c
          apply Quot.inductionOn
            (motive := fun c =>
              ∀b, r c b → Quot.lift (Quot.mk r') h₁ c = Quot.lift (Quot.mk r') h₁ b) c
          clear c
          intro c d
          apply Quot.inductionOn
            (motive := fun d => r (Quot.mk Mcongr c) d →
              Quot.lift (Quot.mk r') h₁ (Quot.mk Mcongr c) = Quot.lift (Quot.mk r') h₁ d) d
          clear d
          intro d rcd; apply Quot.sound; apply rcd)
    have : f ∘ Quot.mk r ∘ Quot.mk Mcongr = Quot.mk r' := rfl
    

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h' : ∀ (x : Cofix F α), r x x
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
x y : M (P F) α
rxy : r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
r' : M (P F) α → M (P F) α → Prop := fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
hr' : r' = fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
a b : M (P F) α
r'ab : r' a b
h₀ :
  (TypeVec.id ::: Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest (P F) a) =
    (TypeVec.id ::: Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest (P F) b)
h₁ : ∀ (u v : M (P F) α), Mcongr u v → Quot.mk r' u = Quot.mk r' v
f : Quot r → Quot r' :=
  Quot.lift (Quot.lift (Quot.mk r') h₁)
    (_ : ∀ (c b : Cofix F α), r c b → Quot.lift (Quot.mk r') h₁ c = Quot.lift (Quot.mk r') h₁ b)
this : f ∘ Quot.mk r ∘ Quot.mk Mcongr = Quot.mk r'
⊢ MvQPF.abs ((TypeVec.id ::: Quot.mk r') <$$> M.dest (P F) a) =
    MvQPF.abs ((TypeVec.id ::: Quot.mk r') <$$> M.dest (P F) b)

Next tactic:
rw [← this, appendFun_comp_id, q.P.comp_map, q.P.comp_map, abs_map, abs_map, abs_map, abs_map,
      h₀]
private theorem Cofix.bisim_aux {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop) (h' : ∀ x, r x x)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  intro x
  rcases x; clear x; rename M (P F) α => x;
  intro y
  rcases y; clear y; rename M (P F) α => y;
  intro rxy
  apply Quot.sound
  let r' := fun x y => r (Quot.mk _ x) (Quot.mk _ y)
  have hr' : r' = fun x y => r (Quot.mk _ x) (Quot.mk _ y) := rfl
  have : IsPrecongr r' := by
    intro a b r'ab
    have h₀ :
      appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P a) =
        appendFun id (Quot.mk r ∘ Quot.mk Mcongr) <$$> MvQPF.abs (M.dest q.P b) :=
      by rw [appendFun_comp_id, comp_map, comp_map]; exact h _ _ r'ab
    have h₁ : ∀ u v : q.P.M α, Mcongr u v → Quot.mk r' u = Quot.mk r' v := by
      intro u v cuv
      apply Quot.sound
      dsimp [hr']
      rw [Quot.sound cuv]
      apply h'
    let f : Quot r → Quot r' :=
      Quot.lift (Quot.lift (Quot.mk r') h₁)
        (by
          intro c
          apply Quot.inductionOn
            (motive := fun c =>
              ∀b, r c b → Quot.lift (Quot.mk r') h₁ c = Quot.lift (Quot.mk r') h₁ b) c
          clear c
          intro c d
          apply Quot.inductionOn
            (motive := fun d => r (Quot.mk Mcongr c) d →
              Quot.lift (Quot.mk r') h₁ (Quot.mk Mcongr c) = Quot.lift (Quot.mk r') h₁ d) d
          clear d
          intro d rcd; apply Quot.sound; apply rcd)
    have : f ∘ Quot.mk r ∘ Quot.mk Mcongr = Quot.mk r' := rfl
    rw [← this, appendFun_comp_id, q.P.comp_map, q.P.comp_map, abs_map, abs_map, abs_map, abs_map,
      h₀]
  

Proof state:
case mk.mk.a
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h' : ∀ (x : Cofix F α), r x x
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
x y : M (P F) α
rxy : r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
r' : M (P F) α → M (P F) α → Prop := fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
hr' : r' = fun x y => r (Quot.mk Mcongr x) (Quot.mk Mcongr y)
this : IsPrecongr r'
⊢ Mcongr x y

Next tactic:
refine' ⟨r', this, rxy⟩
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
⊢ ∀ (x y : Cofix F α), r x y → x = y

Next tactic:
let r' (x y) := x = y ∨ r x y
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
⊢ ∀ (x y : Cofix F α), r x y → x = y

Next tactic:
intro x y rxy
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x y : Cofix F α
rxy : r x y
⊢ x = y

Next tactic:
apply Cofix.bisim_aux r'
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · 

Proof state:
case h'
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x y : Cofix F α
rxy : r x y
⊢ ∀ (x : Cofix F α), r' x x

Next tactic:
intro x
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    

Proof state:
case h'
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y : Cofix F α
rxy : r x✝ y
x : Cofix F α
⊢ r' x x

Next tactic:
left
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    

Proof state:
case h'.h
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y : Cofix F α
rxy : r x✝ y
x : Cofix F α
⊢ x = x

Next tactic:
rfl
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · 

Proof state:
case h
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x y : Cofix F α
rxy : r x y
⊢ ∀ (x y : Cofix F α), r' x y → (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
intro x y r'xy
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    

Proof state:
case h
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
r'xy : r' x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
cases r'xy
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    

Proof state:
case h.inl
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
h✝ : x = y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y
case h.inr
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
h✝ : r x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
case inl h =>
      rw [h]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h✝ : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
h : x = y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
case inl h =>
      rw [h]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h✝ : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
h : x = y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
rw [h]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      rw [h]
    

Proof state:
case h.inr
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
h✝ : r x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
case inr r'xy =>
      have : ∀ x y, r x y → r' x y := fun x y h => Or.inr h
      rw [← Quot.factor_mk_eq _ _ this]
      dsimp
      rw [appendFun_comp_id]
      rw [@comp_map _ _ _ q _ _ _ (appendFun id (Quot.mk r)),
        @comp_map _ _ _ q _ _ _ (appendFun id (Quot.mk r))]
      rw [h _ _ r'xy]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      rw [h]
    

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
r'xy : r x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
case inr r'xy =>
      have : ∀ x y, r x y → r' x y := fun x y h => Or.inr h
      rw [← Quot.factor_mk_eq _ _ this]
      dsimp
      rw [appendFun_comp_id]
      rw [@comp_map _ _ _ q _ _ _ (appendFun id (Quot.mk r)),
        @comp_map _ _ _ q _ _ _ (appendFun id (Quot.mk r))]
      rw [h _ _ r'xy]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      rw [h]
    case inr r'xy =>
      

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
r'xy : r x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
have : ∀ x y, r x y → r' x y := fun x y h => Or.inr h
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      rw [h]
    case inr r'xy =>
      have : ∀ x y, r x y → r' x y := fun x y h => Or.inr h
      

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
r'xy : r x y
this : ∀ (x y : Cofix F α), r x y → r' x y
⊢ (TypeVec.id ::: Quot.mk r') <$$> dest x = (TypeVec.id ::: Quot.mk r') <$$> dest y

Next tactic:
rw [← Quot.factor_mk_eq _ _ this]
/-- Bisimulation principle using `map` and `Quot.mk` to match and relate children of two trees. -/
theorem Cofix.bisim_rel {α : TypeVec n} (r : Cofix F α → Cofix F α → Prop)
    (h : ∀ x y, r x y →
      appendFun id (Quot.mk r) <$$> Cofix.dest x = appendFun id (Quot.mk r) <$$> Cofix.dest y) :
    ∀ x y, r x y → x = y := by
  let r' (x y) := x = y ∨ r x y
  intro x y rxy
  apply Cofix.bisim_aux r'
  · intro x
    left
    rfl
  · intro x y r'xy
    cases r'xy
    case inl h =>
      rw [h]
    case inr r'xy =>
      have : ∀ x y, r x y → r' x y := fun x y h => Or.inr h
      rw [← Quot.factor_mk_eq _ _ this]
      

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
mvf : MvFunctor F
q : MvQPF F
α : TypeVec.{u} n
r : Cofix F α → Cofix F α → Prop
h : ∀ (x y : Cofix F α), r x y → (TypeVec.id ::: Quot.mk r) <$$> dest x = (TypeVec.id ::: Quot.mk r) <$$> dest y
r' : Cofix F α → Cofix F α → Prop := fun x y => x = y ∨ r x y
x✝ y✝ : Cofix F α
rxy : r x✝ y✝
x y : Cofix F α
r'xy : r x y
this : ∀ (x y : Cofix F α), r x y → r' x y
⊢ (TypeVec.id ::: Quot.factor (fun x y => r x y) (fun x y => r' x y) this ∘ Quot.mk fun x y => r x y) <$$> dest x =
    (TypeVec.id ::: Quot.factor (fun x y => r x y) (fun x y => r' x y) this ∘ Quot.mk fun x y => r x y) <$$> dest y

Next tactic:
dsimp