proposition: Lemma vsval_invr w : vsval w \is a GRing.unit -> val w^-1 = (val w)^-1.
proof: Proof. move=> Uu; have def_w: w / w * w = w by rewrite divrK ?vsval_unitr. by apply: (mulrI Uu); rewrite -[in u in u / _]def_w ?mulrK. 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)