proposition: Fact mulC_mulrV : {in unit, right_inverse 1 inv *%R}.
proof: Proof. by move=> x Ux /=; rewrite mulrC mulVx. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)