Entropy generating function for past lifetime and its properties

The past entropy is considered as an uncertainty measure for the past lifetime distribution. Generating function approach to entropy become popular in recent time as it generate several well-known entropy measures. In this paper, we introduce the past entropy-generating function. We study certain properties of this measure. It is shown that the past entropy-generating function uniquely determines the distribution. Further, we present characterizations for some lifetime models using the relationship between reliability concepts and the past entropy-generating function.