proposition: Lemma memv_img f v U : v \in U -> f v \in (f @: U)%VS.
proof: Proof. by move=> Uv; rewrite memvE -limg_line limgS. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)