proposition: Lemma mulrI : {in @unit R, right_injective *%R}.
proof: Proof. by move=> x Ux; apply: can_inj (mulKr Ux). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)