-- Mathlib/Data/QPF/Multivariate/Constructions/Fix.lean
theorem Fix.ind_rec {β : Type u} (g₁ g₂ : Fix F α → β)
    (h :
      ∀ x : F (append1 α (Fix F α)),
        appendFun id g₁ <$$> x = appendFun id g₂ <$$> x → g₁ (Fix.mk x) = g₂ (Fix.mk x)) :
    ∀ x, g₁ x = g₂ x

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ g₁ ⟦(P F).wMk a f' f⟧ = g₂ ⟦(P F).wMk a f' f⟧

Tactic:
rw [← Fix.ind_aux a f' f]

Result:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ g₁ (mk (abs ⟨a, (P F).appendContents f' fun x => ⟦f x⟧⟩)) = g₂ (mk (abs ⟨a, (P F).appendContents f' fun x => ⟦f x⟧⟩))

Proof state:
case a
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ abs ⟨a, (TypeVec.id ::: g₁) ⊚ (P F).appendContents f' fun x => ⟦f x⟧⟩ =
    abs ⟨a, (TypeVec.id ::: g₂) ⊚ (P F).appendContents f' fun x => ⟦f x⟧⟩

Tactic:
congr 2

Result:
case a.e_a.e_snd
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ ((TypeVec.id ::: g₁) ⊚ (P F).appendContents f' fun x => ⟦f x⟧) =
    (TypeVec.id ::: g₂) ⊚ (P F).appendContents f' fun x => ⟦f x⟧

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
⊢ ∀ (a : (P F).A) (f' : (P F).drop.B a ⟹ α) (f : (P F).last.B a → (P F).W α),
    (∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))) →
      g₁ (Quot.mk (⇑(wSetoid α)) ((P F).wMk a f' f)) = g₂ (Quot.mk (⇑(wSetoid α)) ((P F).wMk a f' f))

Tactic:
intro a f' f ih

Result:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ g₁ (Quot.mk (⇑(wSetoid α)) ((P F).wMk a f' f)) = g₂ (Quot.mk (⇑(wSetoid α)) ((P F).wMk a f' f))

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
⊢ (g₁ ∘ fun x => ⟦f x⟧) = g₂ ∘ fun x => ⟦f x⟧

Tactic:
ext x

Result:
case h
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x✝ : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
x : (P F).last.B a
⊢ (g₁ ∘ fun x => ⟦f x⟧) x = (g₂ ∘ fun x => ⟦f x⟧) x

Proof state:
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
⊢ ∀ (x : Fix F α), g₁ x = g₂ x

Tactic:
apply Quot.ind

Result:
case mk
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
⊢ ∀ (a : (P F).W α), g₁ (Quot.mk (⇑(wSetoid α)) a) = g₂ (Quot.mk (⇑(wSetoid α)) a)

Proof state:
case a.e_a.e_snd
n : ℕ
F : TypeVec.{u} (n + 1) → Type u
q : MvQPF F
α : TypeVec.{u} n
β : Type u
g₁ g₂ : Fix F α → β
h : ∀ (x : F (α ::: Fix F α)), (TypeVec.id ::: g₁) <$$> x = (TypeVec.id ::: g₂) <$$> x → g₁ (mk x) = g₂ (mk x)
x : (P F).W α
a : (P F).A
f' : (P F).drop.B a ⟹ α
f : (P F).last.B a → (P F).W α
ih : ∀ (i : (P F).last.B a), g₁ (Quot.mk (⇑(wSetoid α)) (f i)) = g₂ (Quot.mk (⇑(wSetoid α)) (f i))
this : (g₁ ∘ fun x => ⟦f x⟧) = g₂ ∘ fun x => ⟦f x⟧
⊢ splitFun (TypeVec.id ⊚ f') (g₁ ∘ fun x => ⟦f x⟧) = splitFun (TypeVec.id ⊚ f') (g₂ ∘ fun x => ⟦f x⟧)

Tactic:
rw [this]

Result:
no goals