Applications of game theory and search theory to homeland security

This dissertation explores the use of game theory and search theory in the context of terrorism risk and homeland security. Since 9-11 the body of game theoretic literature related to terrorism has grown. What Myerson (1992) termed a "modeling dialogue" is necessary to test and challenge game assumptions and predictions against the realities of the terrorist threat. This dissertation contributes to the homeland security "modeling dialogue" with new models and with an analysis of the current literature.;In the games reviewed in Chapter Three, a centralized defender must allocate a security budget across separate targets or attack scenarios. Chapter Four is concerned with the issue of whether or not there is a justification to invest in defenses against specific attack scenarios given the attacker's ability to switch targets or whether investing all security resources in counterterrorism would be a more effective way to reduce terrorism risk. The chapter contributes to the literature by identifying and making explicit the key assumptions that lead to contradictory results in the current literature on the topic. The chapter also devises a sequential game with incomplete defender information that illustrates the theoretical justification for an overarching security strategy of investing in counterterrorism and in defenses against catastrophic attacks. There are two new findings from this model. First, counterterrorism can shift the threat between targets by increasing the importance of randomness in attacker target selection. Second, sometimes an increase in defenses at high-value targets can increase expected losses from terrorism unless accompanied by a sufficient increase in counterterrorism.