proposition: Lemma eqmxMfull m n p (A : 'M_(m, n)) (B : 'M_(n, p)) : row_full A -> (A *m B :=: B)%MS.
proof: Proof. case/row_fullP=> A' A'A; apply/eqmxP; rewrite submxMl /=. by apply/submxP; exists A'; rewrite mulmxA A'A mul1mx. 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)