proposition: Lemma sub_mask_neg_iff p q : sub_mask p q = IsNeg <-> exists r, p + r = q.
proof: Proof. split. - case sub_mask_spec; try discriminate. intros r Hr _; now exists r. - intros (r,<-). apply sub_mask_add_diag_r. Qed.
imports: BinNums Eqdep_dec EqdepFacts RelationClasses Morphisms Setoid Equalities Orders OrdersFacts GenericMinMax PeanoNat BinPosDef