Module: Mathlib.Computability.TuringMachine.StackTuringMachine

Goal state before:
pp: case succ
K : Type u_1
Γ : K → Type u_2
Λ : Type u_3
σ : Type u_4
inst✝ : DecidableEq K
M : Λ → TM2.Stmt Γ Λ σ
k : K
o : StAct K Γ σ k
q : TM2.Stmt Γ Λ σ
v : σ
S : List (Γ k)
L : ListBlank ((k : K) → Option (Γ k))
hL : ListBlank.map (proj k) L = ListBlank.mk (List.map some S).reverse
n : ℕ
IH :
  n ≤ S.length →
    Reaches₀ (TM1.step (tr M)) { l := some (go k o q), var := v, Tape := Tape.mk' ∅ (addBottom L) }
      { l := some (go k o q), var := v, Tape := (Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)) }
H : n + 1 ≤ S.length
⊢ some
      (bif (some S.reverse[n]).isNone then
        TM1.stepAux (trStAct (goto fun x x_1 ↦ ret q) o) v ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)))
      else
        { l := some (go k o q), var := v,
          Tape := Tape.move Dir.right ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L))) }) =
    some
      { l := some (go k o q), var := v,
        Tape := Tape.move Dir.right ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L))) }

pp: case succ
K : Type u_1
Γ : K → Type u_2
Λ : Type u_3
σ : Type u_4
inst✝ : DecidableEq K
M : Λ → TM2.Stmt Γ Λ σ
k : K
o : StAct K Γ σ k
q : TM2.Stmt Γ Λ σ
v : σ
S : List (Γ k)
L : ListBlank ((k : K) → Option (Γ k))
hL : ListBlank.map (proj k) L = ListBlank.mk (List.map some S).reverse
n : ℕ
IH :
  n ≤ S.length →
    Reaches₀ (TM1.step (tr M)) { l := some (go k o q), var := v, Tape := Tape.mk' ∅ (addBottom L) }
      { l := some (go k o q), var := v, Tape := (Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)) }
H : n + 1 ≤ S.length
⊢ n < S.reverse.length

Tactic:
]

Goal state after:
case succ
K : Type u_1
Γ : K → Type u_2
Λ : Type u_3
σ : Type u_4
inst✝ : DecidableEq K
M : Λ → TM2.Stmt Γ Λ σ
k : K
o : StAct K Γ σ k
q : TM2.Stmt Γ Λ σ
v : σ
S : List (Γ k)
L : ListBlank ((k : K) → Option (Γ k))
hL : ListBlank.map (proj k) L = ListBlank.mk (List.map some S).reverse
n : ℕ
IH :
  n ≤ S.length →
    Reaches₀ (TM1.step (tr M)) { l := some (go k o q), var := v, Tape := Tape.mk' ∅ (addBottom L) }
      { l := some (go k o q), var := v, Tape := (Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)) }
H : n + 1 ≤ S.length
⊢ some
      (bif (some S.reverse[n]).isNone then
        TM1.stepAux (trStAct (goto fun x x_1 ↦ ret q) o) v ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)))
      else
        { l := some (go k o q), var := v,
          Tape := Tape.move Dir.right ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L))) }) =
    some
      { l := some (go k o q), var := v,
        Tape := Tape.move Dir.right ((Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L))) }

case succ
K : Type u_1
Γ : K → Type u_2
Λ : Type u_3
σ : Type u_4
inst✝ : DecidableEq K
M : Λ → TM2.Stmt Γ Λ σ
k : K
o : StAct K Γ σ k
q : TM2.Stmt Γ Λ σ
v : σ
S : List (Γ k)
L : ListBlank ((k : K) → Option (Γ k))
hL : ListBlank.map (proj k) L = ListBlank.mk (List.map some S).reverse
n : ℕ
IH :
  n ≤ S.length →
    Reaches₀ (TM1.step (tr M)) { l := some (go k o q), var := v, Tape := Tape.mk' ∅ (addBottom L) }
      { l := some (go k o q), var := v, Tape := (Tape.move Dir.right)^[n] (Tape.mk' ∅ (addBottom L)) }
H : n + 1 ≤ S.length
⊢ n < S.reverse.length