proposition: Lemma not_in_gotos_terminal l r n X Y : not (In (n, X, Y) gotos) -> terminal M (l, r, goto n X Y).
proof: Proof. move=> Hn y /stepE [] > [] *; subst; try done; apply: Hn; apply: in_combine_r; by eassumption. Qed.
imports: Relation_Operators Operators_Properties Lia PeanoNat List Undecidability.StackMachines.Reductions.CM1_HALT_to_SMNdl_UB.SMX_facts Undecidability.StackMachines.Util(Nat_facts List_facts) ssreflect ssrbool ssrfun