fact: Variable length_preserving_MX : forall s t X s' t' Y b, In ((s, t, X), (s', t', Y), b) MX -> length (s ++ t) = length (s' ++ t') /\ 1 <= length (s ++ t).
imports: Relation_Operators Lia PeanoNat List Undecidability.StackMachines.SMN Undecidability.StackMachines.Util(Nat_facts List_facts Enumerable) Undecidability.StackMachines.Reductions.CM1_HALT_to_SMNdl_UB.CM1_to_SMX ssreflect ssrbool ssrfun