proposition: Lemma compare_sub n m : (n ?= m) = (n - m ?= 0).
proof: Proof. destruct n as [|n|n], m as [|m|m]; simpl; trivial; rewrite <- ? Pos.compare_antisym, ?pos_sub_spec; case Pos.compare_spec; trivial. Qed.
imports: BinNums BinPos Pnat BinNat Bool Equalities GenericMinMax OrdersFacts ZAxioms ZProperties DecidableClass