Before revision:  in order for any two nodes to be linked, a significantly-large number of neighbors must be shared . Naturally, assessing the statistical significance of nodes similarity requires the definition of a proper statistical benchmark: here we consider two recently-proposed null modelsfor bipartite networks, opportunely defined through the exponential random graph formalism .
After revision:  in order for any two nodes to be linked, a significantly-large number of neighbors must be shared . Naturally, assessing the statistical significance of nodes similarity requires the definition of a proper statistical benchmark: here we consider a set of four null models, defined within the Exponential Random Graph framework .