proposition: Lemma row_matrixP A B : (forall i, row i A = row i B) <-> A = B.
proof: Proof. split=> [eqAB | -> //]; apply/matrixP=> i j. by move/rowP/(_ j): (eqAB i); 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)