proposition: Lemma detmx2 a b c d : \det (mx2 a b c d) = a * d - c * b.
proof: Proof. by rewrite det2 mx2_E00 mx2_E01 mx2_E10 mx2_E11. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype matrix mxalgebra bigop zmodp perm choice) dvdring mxstructure minor stronglydiscrete coherent edr