proposition: Lemma rpred_sign (S : smulClosed R) n : (-1) ^+ n \in S.
proof: Proof. by rewrite rpredX ?rpredN1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)