Toward an efficient implementation of the MOCUS algorithm

MOCUS is probably the most famous algorithm to compute minimal cutsets of fault trees. It was proposed by Fussell and Vesely in 1972. It is now the core method of many fault-tree assessment tools. Despite its wide use, textbooks and articles give very few details about how to implement it. This paper describes data structures as well as several improvements and heuristics that make MOCUS very efficient. Experiments on a benchmark of the 1819 event-tree sequences that were generated during a PSA study are reported. Advantages and drawbacks of MOCUS and Binary Decision Diagrams are discussed.