Event-tree analysis by fuzzy probability

A method is presented for dealing with event-tree analysis under uncertainty. Fuzzy-set logic is used to account for imprecision and uncertainty in data while employing event-tree analysis. The fuzzy event-tree logic allows the use of verbal statements for the probabilities and consequences, such as very high, moderate, and low probability. The technique permits an analysis of the qualitative evaluation of the event tree to gain the quantitative results. The application of fuzzy event trees is further demonstrated by using a set of event trees for an electric power protection system to assess the viability of the method in complex situations