cases step with
| charStep le _ step =>
  exact ⟨i, .base le, j, charStep_of_charStep step, εClosure_of_pathIn rest⟩
nfa : NFA
i✝ l : ℕ
c : Char
start : ℕ
cs' : List Char
i j k : ℕ
cs₁ cs₂ cs : List Char
h₂ : cs₂ = []
rest : nfa.pathIn start j k []
ih :
  ∀ {cs : List Char}, cs ++ [c] = cs₂ → ∃ j_1, nfa.pathIn start j j_1 cs ∧ ∃ x ∈ nfa.charStep j_1 c, k ∈ nfa.εClosure x
h : [c] = cs₁ ++ cs₂
h₁ : cs₁ = [c]
step : nfa.stepIn start i j [c]
this : True
⊢ ∃ j, nfa.pathIn start i j [] ∧ ∃ x ∈ nfa.charStep j c, k ∈ nfa.εClosure x
no goals