proposition: Lemma row_free_inj m n p A : row_free A -> injective ((@mulmx F m n p)^~ A).
proof: Proof. case/row_freeP=> A' AK; apply: can_inj (mulmx^~ A') _ => B. by rewrite -mulmxA AK mulmx1. 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 finalg zmodp matrix)