Evaluation of Risk for Acts of Terrorism Using Belief and Fuzzy Sets

Risk is a function of the likelihood of an event and the consequence of that event. There is uncertainty associated with estimating risk for an event that may happen in the future. A terrorist act is not a random event; it is an intentional act by a thinking malevolent adversary. Much of the uncertainty in estimating the risk of a terrorist act is epistemic (state of knowledge) instead of aleatory (stochastic); for example, the adversary knows what acts will be attempted, but we as a defender have incomplete knowledge to know those acts with certainty. To capture the epistemic uncertainty in evaluating the risk from acts of terrorism, we have applied the belief/plausibility measure of uncertainty from the Dempster/Shafer Theory of Evidence. selection of scenarios by an adversary, we have applied approximate reasoning with fuzzy sets. We have developed software in Java to perform these evaluations. We have applied these techniques to cyber security, and to the security of nuclear materials and nuclear weapons. This paper summarizes our work for evaluating risk from acts of terrorism using these techniques. 1,2 Also, to address how we as a defender evaluate the