proposition: Theorem sub_mask_carry_spec p q : sub_mask_carry p q = pred_mask (sub_mask p q).
proof: Proof. revert q. induction p as [p IHp|p IHp|]; intro q; destruct q as [q|q|]; simpl; try reflexivity; rewrite ?IHp; destruct (sub_mask p q) as [|[r|r| ]|] || destruct p; auto. Qed.
imports: BinNums Eqdep_dec EqdepFacts RelationClasses Morphisms Setoid Equalities Orders OrdersFacts GenericMinMax PeanoNat BinPosDef