proposition: Lemma vspaceP U V : U =i V <-> U = V.
proof: Proof. split=> [eqUV | -> //]; apply/subv_anti/andP. by split; apply/subvP=> v; rewrite eqUV. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)