On a Network Centrality Maximization Game
Virtual Informal Systems Seminar (VISS)
Centre for Intelligent Machines (CIM) and Groupe d'Etudes et de Recherche en Analyse des Decisions (GERAD)
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Speaker: Giacomo Como, Professor, Department of Mathematical Sciences, Politecnico di Torino
Abstract:
We study a network formation game where n players, identified with the nodes of a directed graph to be formed, choose where to wire their outgoing links in order to maximize their PageRank centrality. Specifically, the action of every player i consists in the wiring of a predetermined number d(i) of directed out-links, and her utility is her own PageRank centrality in the network resulting from the actions of all players. We show that this is a potential game and that the best response correspondence always exhibits a local structure in that it is never convenient for a node i to link to other nodes that are at incoming distance more than d(i) from her. We then study the equilibria of this game determining necessary conditions for a graph to be a (strict, recurrent) Nash equilibrium. Moreover, in the homogeneous case, where players all have the same number d of out-links, we characterize the structure of the potential maximizing equilibria and, in the special cases d=1 and d=2, we provide a complete classification of the set of (strict, recurrent) ÌýNash equilibria. Our analysis shows in particular that the considered formation mechanism leads to the emergence of undirected and disconnected or loosely connected networks. This is a joint work with Costanza Catalano, Maria Castaldo, and Fabio Fagnani.
Biography:
Giacomo Como is Ìýa ÌýProfessor at Ìýthe Department Ìýof ÌýMathematical ÌýSciences, Politecnico di Torino, Italy. He is also a Senior Lecturer at the Automatic Control Department, Lund University, Sweden. He received the B.Sc., M.S., and Ph.D. degrees in Applied Mathematics Ìýfrom ÌýPolitecnico Ìýdi ÌýTorino, Ìýin Ìý2002, Ìý2004, and 2008, respectively. He was a Visiting Assistant in ÌýResearch at Yale ÌýUniversity in 2006--2007 and a Postdoctoral Associate at Ìýthe ÌýLaboratory Ìýfor ÌýInformation Ìýand ÌýDecision ÌýSystems, ÌýMassachusetts ÌýInstitute of Technology, from 2008 to 2011. He Ìýis Ìýrecipient Ìýof Ìýthe 2015 ÌýGeorge S. Axelby ÌýOutstanding Paper Award. ÌýHis Ìýresearch interests Ìýare in Ìýdynamics, Ìýinformation, Ìýand Ìýcontrol Ìýin Ìýnetwork Ìýsystems Ìýwith Ìýapplications to Ìýcyber-physical Ìýsystems, Ìýinfrastructure Ìýnetworks, Ìýand Ìýsocial and economic networks.
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