Module: Mathlib.Computability.TuringMachine.Tape

Goal state before:
pp: case inr
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
⊢ mk l₁ = mk l₂

Tactic:
cases le_total l₁.length l₂.length <;> [skip; symm] <;> apply this

Goal state after:
case inr.inl.L₁
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₁.length ≤ l₂.length
⊢ ListBlank Γ

case L₂
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₁.length ≤ l₂.length
⊢ ListBlank Γ

case inr.inl.H
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₁.length ≤ l₂.length
⊢ ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1

case inr.inl.h
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₁.length ≤ l₂.length
⊢ l₁.length ≤ l₂.length

case inr.inr.L₁
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₂.length ≤ l₁.length
⊢ ListBlank Γ

case L₂
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₂.length ≤ l₁.length
⊢ ListBlank Γ

case inr.inr.H
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₂.length ≤ l₁.length
⊢ ∀ (i_1 : ℕ), (mk l₂).nth i_1 = (mk l₁).nth i_1

case inr.inr.h
Γ : Type u_1
i : Inhabited Γ
L₁ L₂ : ListBlank Γ
l₁ l₂ : List Γ
H : ∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1
this :
  ∀ {Γ : Type u_1} [i : Inhabited Γ] {L₁ L₂ : ListBlank Γ} (l₁ l₂ : List Γ),
    (∀ (i_1 : ℕ), (mk l₁).nth i_1 = (mk l₂).nth i_1) → l₁.length ≤ l₂.length → mk l₁ = mk l₂
h : ¬l₁.length ≤ l₂.length
h✝ : l₂.length ≤ l₁.length
⊢ l₂.length ≤ l₁.length