Alexander Gutfraind

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The interdiction problem arises in a variety of areas including military logistics, infectious disease control, and counter-terrorism. In the typical formulation of network interdiction, the task of the interdictor is to find a set of edges in a weighted network such that the removal of those edges would maximally increase the cost to an evader of traveling(More)
Complex socioeconomic networks such as transportation networks, information systems and even underground organizations are often designed for resilience-to be able to function even if some of the nodes (e.g. hubs, routers, operatives etc.) are compromised by a human or natural adversary. In many cases the adversary threatens to cause a cascade where the(More)
Relationships between entities in complex systems could be represented using the paradigm of networks. The network representation can then reveal the evolution, structure and dynamics of those systems. Frequently, obtaining the required scientific data about the networks is expensive or infeasible. In other words, the amount of available empirical data is(More)
Complex socioeconomic networks such as information, finance and even terrorist networks need resilience to cascades--to prevent the failure of a single node from causing a far-reaching domino effect. We show that terrorist and guerrilla networks are uniquely cascade-resilient while maintaining high efficiency, but they become more vulnerable beyond a(More)
Major revolts have recently erupted in parts of the Middle East with substantial international repercussions. Predicting, coping with and winning those revolts have become a grave problem for many regimes and for world powers. We propose a new model of such revolts that describes their evolution by building on the classic Lanchester theory of combat. The(More)
Building resilience into today's complex infrastructures is critical to the daily functioning of society and its ability to withstand and recover from natural disasters, epidemics, and cyber-threats. This study proposes quantitative measures that capture and implement the definition of engineering resilience advanced by the National Academy of Sciences. The(More)
Shortest path network interdiction is a combinatorial optimization problem on an activity network arising in a number of important security-related applications. It is classically formulated as a bilevel maximin problem representing an " interdictor " and an " evader ". The evader tries to move from a source node to the target node along a path of the least(More)
People who inject drugs (PWID) are at high risk for blood-borne pathogens transmitted during the sharing of contaminated injection equipment, particularly hepatitis C virus (HCV). HCV prevalence is influenced by a complex interplay of drug-use behaviors, social networks, and geography, as well as the availability of interventions, such as needle exchange(More)