Title:Failures and Recovery in Networks of Networks
Abstract:Network science have been focused on the properties of a single isolated network that does not interact or depend on other networks. In reality, many real-networks, such as power grids, transportation and communication infrastructures interact and depend on other networks. I will present a framework, based on percolation theory, for studying the vulnerability and the recovery of networks of interdependent networks. In interdependent networks, when nodes in one network fail, they cause dependent nodes in other networks to also fail. This is also the case when some nodes like certain locations play a role in two networks --multiplex. This may happen recursively and can lead to a cascade of failures and to a sudden fragmentation of the system. I will present analytical solutions for the critical threshold and the giant component of a network of n interdependent networks. I will show that the general theory of network of networks has many novel features that are not present in the classical network theory of a single network. When recovery of components exists, global spontaneous recovery of the network of networks and hysteresis phenomena occur and the theory suggests an optimal strategy for repairing system of systems. I will also show that interdependent networks embedded in space are significantly more vulnerable compared to non-embedded networks. In particular, small localized attacks of finite fraction, may lead to cascading failures and catastrophic consequences. Thus, analyzing data of real network of networks is highly required to understand the system vulnerability and to design more resilient systems.

Date:23 December 2015(Wednesday)
Time: 2:30pm – 3:30pm (Reception starts at 2:15pm)
Venue: LT 10, 4/F, AC1,City University of Hong Kong
About the Speaker
Prof.Shlomo Havlin was the President of the Israel Physical Society (1996-1999), Dean of Faculty of Exact Sciences (1999-2001) and Chairman of Physics (1984-1988). Havlin received the Landau Prize (Israel, 1988), the Humboldt Senior Scientist Award (Germany, 1992), the Nicholson Medal of the American Physical Society (USA, 2006), the Weizmann Prize (Israel, 2009), the Lilienfeld Prize (USA, 2010), the Rothschild Prize (Israel 2014). Havlin is a Fellow of the American Physical Society and the Institute of Physics in England. He chaired the Excellence National Network Center (1990-2011) and the Minerva Center (1994-2011). He is Editor in Physica A, Fractals and Europhysics Letters. Havlin has made fundamental contributions to statistical physics and its applications in complex networks, climate, medicine, biology, geophysics, and computer science. Recent achievements include: the first theory for the stability of complex networks such as the Internet (PRL, 2000); discovering the ``ultra-small-world'' property of complex networks (PRL, 2003); Introducing fractals in complex networks (Nature, 2005); developing network tools to forecast extreme climate events such as El-Nino (PNAS 2013, 2014); developing the first framework to study interacting networks (Nature, 2010); developing a framework for the robustness of spatial embedded networks of networks (Nature Phys. 2013); introducing recovery in complex networks (Nature Phys. 2014). Havlin published over 700 scientific papers including over 30 Nature and PNAS papers and over 70 PRL. His papers are highly cited, total over 35000 citations (ISI), with more than 3000 citations in the last year. Ten of his papers are between the top 1% highly cited papers in the last 10 years. He has sixty seven papers with over 100 citations and his h-index is 85.

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