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