proposition: Lemma in_igotos_lt {i x} : In (i, x) igotos -> i < length gotos.
proof: Proof. move /in_combine_l /in_seq. by lia. 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