proposition: Lemma scaleNr a v : - a *: v = - (a *: v).
proof: Proof. by apply: (addIr (a *: v)); rewrite -scalerDl !addNr scale0r. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)