simp only [← a2_right_right]
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 : EpsilonArrow σ_0
a2_left : x ∈ M_0.epsilon_arrow_list
a2_right_left : x.start_state = p_0
a2_right_right : List.map (Sum.inr ∘ Sum.inl) x.stop_state_list = xs
⊢ Sum.inl q_0 ∉ xs
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 : EpsilonArrow σ_0
a2_left : x ∈ M_0.epsilon_arrow_list
a2_right_left : x.start_state = p_0
a2_right_right : List.map (Sum.inr ∘ Sum.inl) x.stop_state_list = xs
⊢ Sum.inl q_0 ∉ List.map (Sum.inr ∘ Sum.inl) x.stop_state_list