intro xs x _ _ a3
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_1
q_0 : σ_0
⊢ ∀ (x : List (σ_0 ⊕ σ_1)),
    ∀ x_1 ∈ M_1.epsilon_arrow_list, x_1.start_state = p_0 → List.map Sum.inr x_1.stop_state_list = x → Sum.inl q_0 ∉ x
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_1
q_0 : σ_0
xs : List (σ_0 ⊕ σ_1)
x : EpsilonArrow σ_1
a✝¹ : x ∈ M_1.epsilon_arrow_list
a✝ : x.start_state = p_0
a3 : List.map Sum.inr x.stop_state_list = xs
⊢ Sum.inl q_0 ∉ xs