proposition: Lemma expv_id A n : (A ^+ n.+1)%VS = A.
proof: Proof. by elim: n => // n IHn; rewrite !expvSl prodvA prodv_id -expvSl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype div tuple finfun bigop ssralg) mathcomp(finalg zmodp matrix vector poly)