fact: Definition ltmx F m1 m2 n (A : 'M[F]_(m1, n)) (B : 'M_(m2, n)) := (A <= B)%MS && ~~ (B <= A)%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)