Geoforensics leverages various spatial analytical, biological, ecological, and geological techniques to improve criminal investigations, including efforts thwart terrorism, evaluate humanitarian crises or identify the origin of fraudulent goods. In addition investigating what took place, geoforensic often focus on determining where when event occurred. Forensic palynology is a promising subfiel...

We consider two network interdiction problems: one where a network user tries to traverse a network from a starting vertex s to a target vertex t along the shortest path while an interdictor tries to eliminate all short s-t paths by destroying as few vertices (arcs) as possible, and one where the network user, as before, tries to traverse the network from s to t along the shortest path while th...

We study variants of the classic s-t cut problem and prove the following improved hardness results assuming the Unique Games Conjecture (UGC). • For any constant k ≥ 2 and ǫ > 0, we show that Directed Multicutwith k source-sink pairs is hard to approximate within a factor k − ǫ. This matches the trivial k-approximation algorithm. By a simple reduction, our result for k = 2 implies that Directed...

Vulnerability to sudden service disruptions due to deliberate sabotage and terrorist attacks is one of the major threats of today. Whereas the design of reliable supply networks has received considerable attention in the last few decades, few authors have addressed the issue of optimizing security investments for existing, but vulnerable, systems. In this paper we consider a simple service/supp...

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy REFORMULATION AND CUTTING-PLANE APPROACHES FOR SOLVING TWO-STAGE OPTIMIZATION AND NETWORK INTERDICTION PROBLEMS By Siqian Shen August 2011 Chair: J. Cole Smith Major: Industrial and Systems Engineering This dissertation investigates mode...

BACKGROUND The US invests considerable effort in searching and interdicting drug-trafficking vessels in the Caribbean and Eastern Pacific regions. While some vessels are indeed interdicted, resulting in confiscation of substantial quantities of drugs, many such vessels manage to avoid detection and arrive safely at their destinations in Central America and Mexico with their drug load intact. Th...

Today’s organizations are inherently open and connected, sharing knowledge and ideas in order to remain innovative. As a result, these organizations are also more vulnerable to information theft through different forms of security breaches caused by hackers and competitors. One way of understanding the vulnerability of an information system is to build and analyze the attack graph of that syste...