proposition: Lemma matrix0Pn m n (A : 'M_(m, n)) : reflect (exists i j, A i j != 0) (A != 0).
proof: Proof. by rewrite matrix_eq0; apply/(iffP forallPn) => -[i /forallPn]; exists i. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)