simp at h
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
inv : LowerInvεClosure nfa next stack
hemp : ¬stack.isEmpty = true
h :
  (let entry := stack.back' hemp;
    let stack' := stack.pop;
    let_fun this := ⋯;
    match entry with
    | StackEntry.explore target => exploreεClosure nfa pos next currentSave matched saveSlots target stack'
    | StackEntry.restore save => εClosure nfa pos next save matched saveSlots stack') =
    (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
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 : LowerInvεClosure nfa next stack
hemp : ¬stack.isEmpty = true
h :
  (match stack.back' hemp with
    | StackEntry.explore target => exploreεClosure nfa pos next currentSave matched saveSlots target stack.pop
    | StackEntry.restore save => εClosure nfa pos next save matched saveSlots stack.pop) =
    (matched', next', saveSlots')
⊢ LowerInvεClosure nfa next' #[]