case _ x a2 =>
  cases a2
  case _ a2_left a2_right =>
    cases a2_right
    case _ a2_right_left a2_right_right =>
      simp only [← a2_right_right]
      simp
α : Type
inst✝ : DecidableEq α
σ_0 σ_1 : Type
M_0 : EpsilonNFA α σ_0
M_1 : EpsilonNFA α σ_1
p_0 : σ_0
q_0 : ℕ
xs : List (ℕ ⊕ σ_0 ⊕ σ_1)
x : σ_0
a2 : x ∈ M_0.accepting_state_list ∧ x = p_0 ∧ List.map (Sum.inr ∘ Sum.inr) M_1.starting_state_list = xs
⊢ Sum.inl q_0 ∉ xs
no goals