proposition: Lemma rregX x n : rreg x -> rreg (x ^+ n).
proof: Proof. by move/(@lregX R^c x n); rewrite revrX. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)