TALK BY Riccardo DI Clemente: Randomizing bipartite networks: the case of the World Trade Web.

CCS’15 Conference on Complex Systems. (Phoenix, AZ, USA)

Within the last fteen years, network theory has been successfully applied both to natural sciences and to socioeconomic disciplines. In particular, bipartite networks have been recognized to provide a particularly insightful representation of many systems, ranging from mutualistic networks in ecology to trade networks in economy, whence the need of a pattern detection-oriented analysis in order

to identify statistically-signi cant structural properties. Such an analysis rests upon the de nition
of suitable null models, i.e. upon the choice of the portion of network structure to be preserved while randomizing everything else. However, quite surprisingly, little work has been done so far
to de ne null models for real bipartite networks. The aim of the present work is to ll this gap, extending a recently-proposed method to randomize monopartite networks to bipartite networks. While the proposed formalism is perfectly general, we apply our method to the binary, undirected, bipartite representation of the World Trade Web, comparing the observed values of a number of structural quantities of interest with the expected ones, calculated via our randomization procedure. Interestingly, the behavior of the World Trade Web in this new representation is strongly di erent from the monopartite analogue, showing highly non-trivial patterns of self-organization.