proposition: Lemma minor2 m n (A : 'M[R]_(m,n)) (f : 'I_2 -> 'I_m) (g : 'I_2 -> 'I_n) : minor f g A = A (f 0) (g 0) * A (f 1) (g 1) - A (f 1) (g 0) * A (f 0) (g 1).
proof: Proof. by rewrite /minor det2 !mxE. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path ssralg) mathcomp(fintype perm choice finfun matrix bigop zmodp poly mxpoly)