proposition: Lemma tofrac_eq0 (p : R): (p%:F == 0) = (p == 0).
proof: Proof. by rewrite tofrac_eq. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(ssrAC choice tuple bigop ssralg poly polydiv) mathcomp(generic_quotient)