Module: Mathlib.Computability.TuringMachine.PostTuringMachine

Goal state before:
pp: case some.refine_1
Γ : Type u_1
inst✝¹ : Inhabited Γ
Λ : Type u_2
inst✝ : Inhabited Λ
M : TM0.Machine Γ Λ
x✝ : TM0.Cfg Γ Λ
q : Λ
T : Tape Γ
q' : Λ
s : TM0.Stmt Γ
this :
  TM1.step (tr M) { l := some (Λ'.act s q'), var := (), Tape := T } =
    some
      { l := some (Λ'.normal q'), var := (),
        Tape :=
          match s with
          | TM0.Stmt.move d => Tape.move d T
          | TM0.Stmt.write a => Tape.write a T }
e : M q T.head = some (q', s)
⊢ { l := some (Λ'.act s q'), var := (), Tape := T } ∈ TM1.step (tr M) { l := some (Λ'.normal q), var := (), Tape := T }

pp: case some.refine_2
Γ : Type u_1
inst✝¹ : Inhabited Γ
Λ : Type u_2
inst✝ : Inhabited Λ
M : TM0.Machine Γ Λ
x✝ : TM0.Cfg Γ Λ
q : Λ
T : Tape Γ
q' : Λ
s : TM0.Stmt Γ
this :
  TM1.step (tr M) { l := some (Λ'.act s q'), var := (), Tape := T } =
    some
      { l := some (Λ'.normal q'), var := (),
        Tape :=
          match s with
          | TM0.Stmt.move d => Tape.move d T
          | TM0.Stmt.write a => Tape.write a T }
e : M q T.head = some (q', s)
⊢ ReflTransGen (fun a b ↦ b ∈ TM1.step (tr M) a)
    { l := some (Λ'.normal q'), var := (),
      Tape :=
        match s with
        | TM0.Stmt.move d => Tape.move d T
        | TM0.Stmt.write a => Tape.write a T }
    {
      l :=
        match
          match
            M q'
              (match s with
                | TM0.Stmt.move d => Tape.move d T
                | TM0.Stmt.write a => Tape.write a T).head with
          | some val => true
          | none => false with
        | true => some (Λ'.normal q')
        | false => none,
      var := (),
      Tape :=
        match s with
        | TM0.Stmt.move d => Tape.move d T
        | TM0.Stmt.write a => Tape.write a T }

Tactic:
<;>

Goal state after:
case some.refine_1
Γ : Type u_1
inst✝¹ : Inhabited Γ
Λ : Type u_2
inst✝ : Inhabited Λ
M : TM0.Machine Γ Λ
x✝ : TM0.Cfg Γ Λ
q : Λ
T : Tape Γ
q' : Λ
s : TM0.Stmt Γ
this :
  TM1.step (tr M) { l := some (Λ'.act s q'), var := (), Tape := T } =
    some
      { l := some (Λ'.normal q'), var := (),
        Tape :=
          match s with
          | TM0.Stmt.move d => Tape.move d T
          | TM0.Stmt.write a => Tape.write a T }
e : M q T.head = some (q', s)
⊢ { l := some (Λ'.act s q'), var := (), Tape := T } ∈ TM1.step (tr M) { l := some (Λ'.normal q), var := (), Tape := T }

case some.refine_2
Γ : Type u_1
inst✝¹ : Inhabited Γ
Λ : Type u_2
inst✝ : Inhabited Λ
M : TM0.Machine Γ Λ
x✝ : TM0.Cfg Γ Λ
q : Λ
T : Tape Γ
q' : Λ
s : TM0.Stmt Γ
this :
  TM1.step (tr M) { l := some (Λ'.act s q'), var := (), Tape := T } =
    some
      { l := some (Λ'.normal q'), var := (),
        Tape :=
          match s with
          | TM0.Stmt.move d => Tape.move d T
          | TM0.Stmt.write a => Tape.write a T }
e : M q T.head = some (q', s)
⊢ ReflTransGen (fun a b ↦ b ∈ TM1.step (tr M) a)
    { l := some (Λ'.normal q'), var := (),
      Tape :=
        match s with
        | TM0.Stmt.move d => Tape.move d T
        | TM0.Stmt.write a => Tape.write a T }
    {
      l :=
        match
          match
            M q'
              (match s with
                | TM0.Stmt.move d => Tape.move d T
                | TM0.Stmt.write a => Tape.write a T).head with
          | some val => true
          | none => false with
        | true => some (Λ'.normal q')
        | false => none,
      var := (),
      Tape :=
        match s with
        | TM0.Stmt.move d => Tape.move d T
        | TM0.Stmt.write a => Tape.write a T }