Bolthausen, Erwin et Kistler, Nicola, On a nonhierarchical version of the generalized random energy model, Annals of applied probability , 16(1), 2006, pp. 1-14
We introduce a natural nonhierarchical version of Derrida.s generalized random energy model. We prove that, in the thermodynamical limit, the free energy is the same as that of a suitably constructed GREM.