proposition: Lemma detV (A : 'M_n) : \det A^-1 = (\det A)^-1.
proof: Proof. exact: det_inv. 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)