proposition: Lemma mulf_neq0 x y : x != 0 -> y != 0 -> x * y != 0.
proof: Proof. by move=> x0 y0; rewrite mulf_eq0; apply/norP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)