Theorem: Regex.VM.stepChar_spec.preserve_cls
Proof state before:
case h_1
nfa : NFA
c : Char
pos : String.Pos
next : SparseSet nfa.nodes.size
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
target : Fin nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
inv : ∀ (i j : Fin nfa.nodes.size), i ∈ next → ↑j ∈ nfa.εStep ↑i → j ∈ next
c'✝ : Char
target'✝ : ℕ
heq✝ : nfa[target] = Node.char c'✝ target'✝
h :
  (if c = c'✝ then
      let_fun isLt := ⋯;
      let currentSave := saveSlots.get ↑target ⋯;
      exploreεClosure nfa pos next currentSave none saveSlots ⟨target'✝, isLt⟩ #[]
    else (none, next, saveSlots)) =
    (matched', next', saveSlots')
⊢ ∀ (i j : Fin nfa.nodes.size), i ∈ next' → ↑j ∈ nfa.εStep ↑i → j ∈ next'

case h_2
nfa : NFA
c : Char
pos : String.Pos
next : SparseSet nfa.nodes.size
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
target : Fin nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
inv : ∀ (i j : Fin nfa.nodes.size), i ∈ next → ↑j ∈ nfa.εStep ↑i → j ∈ next
cs✝ : Data.Classes
target'✝ : ℕ
heq✝ : nfa[target] = Node.sparse cs✝ target'✝
h :
  (if c ∈ cs✝ then
      let_fun isLt := ⋯;
      let currentSave := saveSlots.get ↑target ⋯;
      exploreεClosure nfa pos next currentSave none saveSlots ⟨target'✝, isLt⟩ #[]
    else (none, next, saveSlots)) =
    (matched', next', saveSlots')
⊢ ∀ (i j : Fin nfa.nodes.size), i ∈ next' → ↑j ∈ nfa.εStep ↑i → j ∈ next'

case h_3
nfa : NFA
c : Char
pos : String.Pos
next : SparseSet nfa.nodes.size
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
target : Fin nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
inv : ∀ (i j : Fin nfa.nodes.size), i ∈ next → ↑j ∈ nfa.εStep ↑i → j ∈ next
x✝¹ : ∀ (c' : Char) (target' : ℕ), nfa[target] = Node.char c' target' → False
x✝ : ∀ (cs : Data.Classes) (target' : ℕ), nfa[target] = Node.sparse cs target' → False
h : (none, next, saveSlots) = (matched', next', saveSlots')
⊢ ∀ (i j : Fin nfa.nodes.size), i ∈ next' → ↑j ∈ nfa.εStep ↑i → j ∈ next'
Tactic:
next =>
  split at h
  next =>
    simp at h
    exact exploreεClosure_spec.preserve_cls h inv
  next =>
    simp at h
    simp only [←h]
    exact inv
Proof state after:
case h_2
nfa : NFA
c : Char
pos : String.Pos
next : SparseSet nfa.nodes.size
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
target : Fin nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
inv : ∀ (i j : Fin nfa.nodes.size), i ∈ next → ↑j ∈ nfa.εStep ↑i → j ∈ next
cs✝ : Data.Classes
target'✝ : ℕ
heq✝ : nfa[target] = Node.sparse cs✝ target'✝
h :
  (if c ∈ cs✝ then
      let_fun isLt := ⋯;
      let currentSave := saveSlots.get ↑target ⋯;
      exploreεClosure nfa pos next currentSave none saveSlots ⟨target'✝, isLt⟩ #[]
    else (none, next, saveSlots)) =
    (matched', next', saveSlots')
⊢ ∀ (i j : Fin nfa.nodes.size), i ∈ next' → ↑j ∈ nfa.εStep ↑i → j ∈ next'

case h_3
nfa : NFA
c : Char
pos : String.Pos
next : SparseSet nfa.nodes.size
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
target : Fin nfa.nodes.size
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
inv : ∀ (i j : Fin nfa.nodes.size), i ∈ next → ↑j ∈ nfa.εStep ↑i → j ∈ next
x✝¹ : ∀ (c' : Char) (target' : ℕ), nfa[target] = Node.char c' target' → False
x✝ : ∀ (cs : Data.Classes) (target' : ℕ), nfa[target] = Node.sparse cs target' → False
h : (none, next, saveSlots) = (matched', next', saveSlots')
⊢ ∀ (i j : Fin nfa.nodes.size), i ∈ next' → ↑j ∈ nfa.εStep ↑i → j ∈ next'