simp
case step
nfa : NFA
i j : ℕ
cs : List Char
k : 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 : nfa.pathIn start k✝ k cs' → nfa.pathIn start j✝ k (cs₂✝ ++ cs')
path₂ : nfa.pathIn start k✝ k cs'
⊢ nfa.pathIn start i✝ k (cs₁✝ ++ cs₂✝ ++ cs')
case step
nfa : NFA
i j : ℕ
cs : List Char
k : 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 : nfa.pathIn start k✝ k cs' → nfa.pathIn start j✝ k (cs₂✝ ++ cs')
path₂ : nfa.pathIn start k✝ k cs'
⊢ nfa.pathIn start i✝ k (cs₁✝ ++ (cs₂✝ ++ cs'))