proposition: Lemma trmx_adj : forall n (A : 'M_n), (adjugate A)^T === adjugate A^T.
proof: Proof. by move=> n A i j; rewrite /adjugate; rewrite -> cofactor_tr; rewrite /trmx; reflexivity. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq choice fintype finfun bigops ssralg groups perm zmodp morphisms Ring RingClass bigopsClass Setoid Morphisms