exact ih
case step
nfa : NFA
i j : ℕ
cs : List Char
start i✝ j✝ k✝ : ℕ
cs₁✝ cs₂✝ : List Char
step✝ : nfa.stepIn start i✝ j✝ cs₁✝
rest✝ : nfa.pathIn start j✝ k✝ cs₂✝
ih : start ≤ k✝
⊢ start ≤ k✝
no goals