Section CompositionSeries.
Variable gT : finGroupType.
Local Notation gTg := {group gT}.
Implicit Types (G : gTg) (s : seq gTg).
Local Notation compo := [rel x y : {set gT} | maxnormal y x x].
Definition comps G s := ((last G s) == 1%G) && compo.-series G s.
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(* The factors associated to two composition series of the same group are     *)
(* the same up to isomorphism and permutation                                 *)
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Lemma JordanHolderUniqueness (G : gTg) (s1 s2 : seq gTg) :
comps G s1 -> comps G s2 -> perm_eq (mkfactors G s1) (mkfactors G s2).