proposition: Lemma fullrowsub_full : row_full (rowsub frf A).
proof: Proof. by rewrite mxsub_ffunl rowsub_comp rowsub_cast esymK row_full_castmx. 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)