Our daily lives can be maintained by the high-technology systems. Computer systems are typical examples of such systems. We can enjoy our modern lives by using many computer systems. Much more importantly, we have to maintain such systems without failure, but cannot predict when such systems will fail and how to fix such systems without delay. A stochastic process is a set of outcomes of a random experiment indexed by time, and is one of the key tools needed to analyze the future behavior quantitatively. Reliability and maintainability technologies are of great interest and importance to the...

In Japan there are many research workers who are especially inter- ested in stochastic models in reliability theory. On the above back- ground, it was a nice occasion for the Editors to organize the Reliabil- ity Symposium with emphasis on "Stochastic Models in Reliability Theory." The Reliability Symposium was held in Nagoya, Japan, April 23-24, 1984. In the Symposium there were 14 contributions of the recent research works on stochastic models in reliability theory in Japan. We briefly sketch all the contributions by the following classifications just for conveni- ence. The first three...