proposition: Lemma matrixP (A B : matrix R m n) : A =2 B <-> A = B.
proof: Proof. rewrite /fun_of_matrix; split=> [/= eqAB | -> //]. by apply/val_inj/ffunP=> [[i j]]; apply: eqAB. 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)