proposition: Lemma GL_det u : \det u != 0.
proof: Proof. by apply: contraL (GL_unitmx u); rewrite unitmxE => /eqP->; rewrite unitr0. 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)