proposition: Lemma unitr_trmx (A : 'M_n) : (A^T \is a GRing.unit) = (A \is a GRing.unit).
proof: Proof. exact: unitmx_tr. 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)