A complex system that is neither in series nor parallel is shown in Figure G-1. The reliability is evaluated

using the theorem on total probability:

(G-1)

Select a critical component. In this case, select component A. The system can function with or without

it, and in each case the system resolves into a simpler system that is easily analyzed. If A works, it does

not matter if B1 or B2 is working. The system can then be represented by the reliability block diagram in

Figure G-2.

If component A does not work, the system can be reduced to Figure G-3.

Figure G-2 is evaluated as follows:

(G-2)