proposition: Lemma scalerN a v : a *: (- v) = - (a *: v).
proof: Proof. by apply: (addIr (a *: v)); rewrite -scalerDr !addNr scaler0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)