proposition: Lemma det_mx00 (A : 'M[R]_0) : \det A = 1.
proof: Proof. by rewrite flatmx0 -(flatmx0 1%:M) det1. 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)