proposition: Lemma cV0Pn n (v : 'cV_n) : reflect (exists i, v i 0 != 0) (v != 0).
proof: Proof. apply: (iffP (matrix0Pn _)) => [[i] [j]|[i]]; last by exists i, 0. by rewrite ord1; 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)