Section JordanHolder.
Variables (gT : finGroupType) (G : {group gT}).
Variables (n : nat) (rG : mx_representation F G n).
Local Notation modG := ((mxmodule rG) n).
Definition section_repr U V (modU : modG U) (modV : modG V) :=
submod_repr (section_module modU modV).

Lemma mx_factmod_sub U modU :
mx_rsim (@section_repr U _ modU (mxmodule1 rG)) (factmod_repr modU).