fact: Structure proper_mxsum_expr n := ProperMxsumExpr { proper_mxsum_val :> 'M_n; proper_mxsum_rank : nat; _ : mxsum_spec proper_mxsum_val proper_mxsum_rank }.
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)