have isLt := nfa.inBounds' target hn
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
target : Fin 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
inv : LowerInvExploreεClosure nfa next target stack
h✝ : target ∉ next
target₁ target₂ : ℕ
hn : nfa[↑target] = Node.split target₁ target₂
h :
  exploreεClosure nfa pos (next.insert target) currentSave matched saveSlots ⟨target₁, ⋯⟩
      (stack.push (StackEntry.explore ⟨target₂, ⋯⟩)) =
    (matched', next', saveSlots')
⊢ LowerInvεClosure nfa next' #[]
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
target : Fin 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
inv : LowerInvExploreεClosure nfa next target stack
h✝ : target ∉ next
target₁ target₂ : ℕ
hn : nfa[↑target] = Node.split target₁ target₂
h :
  exploreεClosure nfa pos (next.insert target) currentSave matched saveSlots ⟨target₁, ⋯⟩
      (stack.push (StackEntry.explore ⟨target₂, ⋯⟩)) =
    (matched', next', saveSlots')
isLt : (Node.split target₁ target₂).inBounds nfa.nodes.size
⊢ LowerInvεClosure nfa next' #[]