proposition: Lemma rank_rV n (v : 'rV[F]_n) : \rank v = (v != 0).
proof: Proof. case: eqP => [-> | nz_v]; first by rewrite mxrank0. by apply/eqP; rewrite eqn_leq rank_leq_row lt0n mxrank_eq0; apply/eqP. 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 finalg zmodp matrix)