proposition: Lemma capv_idPr {U V} : reflect (U :&: V = V)%VS (V <= U)%VS.
proof: Proof. by rewrite capvC; apply: capv_idPl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)