On a generalization of a waiting time problem and some combinatorial identities

Abstract

In this paper we give an extension of the results of the generalized waiting time problem given by El-Desouky and Hussen (1990). An urn contains m types of balls of unequal numbers, and balls are drawn with replacement until first duplication. In the case of finite memory of order k, let n_i be the number of type i, i = 1, 2, . . ., m. The probability of success p_i = n_i / N, i = 1, 2, . . ., m, where n_i is a positive integer and N = ∑_i=1^mn_i. Let Y_m,k be the number of drawings required until first duplication. We obtain some new expressions of the probability function, in terms of Stirling numbers, symmetric polynomials, and generalized harmonic numbers. Moreover, some special cases are investigated. Finally, some important new combinatorial identities are obtained.