proposition: Lemma cofactor_tr n (A : 'M[R]_n) i j : cofactor A^T i j = cofactor A j i.
proof: Proof. rewrite /cofactor addnC; congr (_ * _). rewrite -tr_row' -tr_col' det_tr; congr (\det _). by apply/matrixP=> ? ?; rewrite !mxE. 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)