fact: Variable M : list mm2_instr.
imports: List PeanoNat Lia Relation_Operators Operators_Properties ConstructiveEpsilon Undecidability.MinskyMachines.MM2 Undecidability.MinskyMachines.Deciders.MM2_UBOUNDED_dec Undecidability.MinskyMachines.Util.MM2_facts ssreflect ssrbool ssrfun