proposition: Lemma congr_subvs u v : u = v -> vsval u = vsval v.
proof: Proof. exact: congr1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)