proposition: Lemma vsprojK : {in U, cancel vsproj vsval}.
proof: Proof. by rewrite unlock; apply: projv_id. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)