fact: Definition has_mxring_id m n (R : 'A[F]_(m , n)) := (R != 0) && (row_mx 0 (row_mx (mxvec R) (mxvec R)) <= row_mx (cokermx R) (row_mx (lin_mx (mulmx R \o lin_mulmx)) (lin_mx (mulmx R \o lin_mulmxr))))%MS.
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)