simp [εStep, Node.εStep, hn] at hj
case inl
nfa : NFA
pos : String.Pos
next : SparseSet nfa.nodes.size
currentSave : Array (Option String.Pos)
matched : Option (Array (Option String.Pos))
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
stack : Array (StackEntry nfa.nodes.size)
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
offset✝ target' : ℕ
isLt : (Node.save offset✝ target').inBounds nfa.nodes.size
h✝¹ : offset✝ < currentSave.size
i j : Fin nfa.nodes.size
hj : ↑j ∈ nfa.εStep ↑i
inv : LowerInvExploreεClosure nfa next i stack
h✝ : i ∉ next
hn : nfa[↑i] = Node.save offset✝ target'
h :
  exploreεClosure nfa pos (next.insert i) (currentSave.set ⟨offset✝, ⋯⟩ (some pos)) matched saveSlots ⟨target', ⋯⟩
      (stack.push (StackEntry.restore currentSave)) =
    (matched', next', saveSlots')
hi : i ∈ next.insert i
⊢ j ∈ next.insert i ∨ j = ⟨target', isLt⟩ ∨ StackEntry.explore j ∈ stack.push (StackEntry.restore currentSave)
case inl
nfa : NFA
pos : String.Pos
next : SparseSet nfa.nodes.size
currentSave : Array (Option String.Pos)
matched : Option (Array (Option String.Pos))
saveSlots : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
stack : Array (StackEntry nfa.nodes.size)
matched' : Option (Array (Option String.Pos))
next' : SparseSet nfa.nodes.size
saveSlots' : Data.Vec (Array (Option String.Pos)) nfa.nodes.size
offset✝ target' : ℕ
isLt : (Node.save offset✝ target').inBounds nfa.nodes.size
h✝¹ : offset✝ < currentSave.size
i j : Fin nfa.nodes.size
inv : LowerInvExploreεClosure nfa next i stack
h✝ : i ∉ next
hn : nfa[↑i] = Node.save offset✝ target'
h :
  exploreεClosure nfa pos (next.insert i) (currentSave.set ⟨offset✝, ⋯⟩ (some pos)) matched saveSlots ⟨target', ⋯⟩
      (stack.push (StackEntry.restore currentSave)) =
    (matched', next', saveSlots')
hi : i ∈ next.insert i
hj : ↑j = target'
⊢ j ∈ next.insert i ∨ j = ⟨target', isLt⟩ ∨ StackEntry.explore j ∈ stack.push (StackEntry.restore currentSave)