Font Size: 

Multiplex arises when the  network for the same set of nodes is repetitively observed on different layers that can represent, for instance, different  statistical units or  different criteria to connect the nodes. A multi-level Stochastic Blockmodel for multiplexes is introduced to provide a joint clustering of  layers and nodes. This is achieved by considering two different sets of discrete latent variables. A former set allows us identifying groups of layers sharing similar connectivity patterns. A letter set of discrete latent variables, nested within the former, allows us identifying groups of nodes sharing similar relational features. A variational Expectation-Maximization algorithm is derived for estimation purposes.