fact: Definition maxrankfun : 'I_m ^ \rank A := [arg max_(f > finfun (widen_ord (rank_leq_row A))) \rank (rowsub f A)].
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)