Multivariate q-Pólya and inverse q-Pólya distributions

Abstract

An urn containing specified numbers of balls of distinct ordered colors is considered. A multiple q-Pólya urn model is introduced by assuming that the probability of q-drawing a ball of a specific color from the urn varies geometrically, with rate q, both with the number of drawings and the number of balls of the specific color, together with the total number of balls of the preceded colors, drawn in the previous q-drawings. Then, the joint distributions of the numbers of balls of distinct colors drawn (a) in a specific number of q-drawings and (b) until the occurrence of a specific number of balls of a certain color, are derived. These two distributions turned out to be q-analogues of the multivariate Pólya and inverse Pólya distributions, respectively. Also, the limiting distributions of the multivariate q-Pólya and inverse q-Pólya distributions, as the initial total number of balls in the urn tends to infinity, are shown to be q-multinomial and negative q-multinomial distributions, respectively.