Modularizing and Minimizing Fault Trees

The analysis of a fault-tree by Locks showed that computation could be eased by modularizing the fault-tree. His process involves hand calculation and insight from the analyst. Many computer algorithms for minimizing a fault tree rely on a brute force method which leads to computational buildup. Approaches which simplify a tree by inspection and hand calculation can often be programed and form a useful tool for pre-analysis of a fault tree. This paper demonstrates that the process of modularizing can be organised by a simple computer program which can roughly analyse the fault tree prior to further analysis by a more sophisticated minimizing program. The methods allow some of the benefits of inspection to be incorporated into a computer program.