A direct approach to obtain tighter bounds for large fault trees with repeated events

This paper presents a direct approach to provide a bound on the probability of occurrence of the TOP event in large fault trees with repeated events. Our method uses the concept of a cutting heuristic discussed in the literature to obtain the signal probabilities for testability measurement in logic circuits. The method is efficient and solves coherent and noncoherent fault trees with repeated events and having standard gates such as AND, OR, XOR and NOT gates. Examples are used to illustrate the approach