1. A method for use in computer controlled detection and indication of a malfunction in a system, said method comprising the steps of: providing a plural level fault tree wherein alternative true and false decisions are arranged as information nodes of a data array to be examined in a sequence to lead to a conclusion; examining nodes in a predetermined first path for true (T) or false (F) status; examining subsequent nodes in accordance with the expressions EQU A(T).sub.n+1 =A.sub.n +2.sup.L for true results EQU A(F).sub.n+1 =A.sub.n +2(2.sup.L) for false results where A=node number, L=tree level, and n=present node being examined, until a conclusion is reached.