Closure of the NBUE (New Better than Used in Expectation) and DMRL (Decreasing Mean Residual Life) Classes under Formation of Parallel Systems

摘要

The class of new better than used in expectation life distributions is shown to be closed under the formation of parallel systems with independent and identically distributed components. The class of differentiable life distributions with decreasing mean residual life is also proved to have the same closure property.