proposition: Lemma matrix_nonzero1 : 1%:M != 0 :> 'M[R]_n.
proof: Proof. by apply/eqP=> /matrixP/(_ 0 0)/eqP; rewrite !mxE oner_eq0. 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)