ABSTRACT
As already introduced in the previous chapter, after a renewal a system is "as good as new"; i.e. after its renewal a system has the same lifetime distribution as at the moment of its installation. The formal subject of renewal theory is a simple main tenance policy: A system is renewed on every failure in negligible time and after that it immediately starts continuing its work. In what follows, this policy is refer red to as policy 0. It reflects practical situations when failed (sub-) systems are completely replaced by equivalent (sub-) systems. In such cases renewal theory provides the mathematical tools for organising a stable production process. At the same time it yields the mathematical foundations for analyzing the behaviour of complicated systems in the running time of which renewal points are "imbedded" in a sense that will be defined more precisely later.
