proposition: Lemma tofracM : {morph tofrac: x y / x * y}.
proof: Proof. exact: rmorphM. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(ssrAC choice tuple bigop ssralg poly polydiv) mathcomp(generic_quotient)