## Ordering conditional lifetimes of coherent systems.(English)Zbl 1111.60012

Summary: Consider a system of $$n$$ components that has the property that there exists a number $$r$$ $$(r<n)$$, such that if it is known that at most $$r$$ components have failed, the system is still functioning with probability 1. Suppose that such a system is equipped with a warning light that comes up at the time of the failure of the $$r$$th component. The system is still working then, and we are interested in its residual life. In this paper we obtain some results which stochastically compare the residual lives of such systems with the same type, or with different types, of components. Some applications are given. In particular, we derive upper and lower bounds on the expected residual lives of such systems given that the warning light has not come up yet, and given that the component hazard rate functions are bounded from below or from above by a known constant.

### MSC:

 60E15 Inequalities; stochastic orderings 60K10 Applications of renewal theory (reliability, demand theory, etc.) 62G30 Order statistics; empirical distribution functions
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### References:

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