proposition: Lemma increase_try_step_shape {y l r i} : SMX.step M (l, r, '$?i) y -> (l = [§1] ++ [§0] ++ skipn 2 l) \/ (l = [§1] ++ [§1] ++ skipn 2 l).
proof: Proof. move=> /stepE [] > [] *; subst; try done; [by left | by right]. 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