proposition: Lemma adjoinSl U V x : (U <= V -> <<U; x>> <= <<V; x>>)%VS.
proof: Proof. by move=> sUV; rewrite agenvS ?addvS. 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)