Exactly Solvable Balanced Tenable Urns with Random Entries via the   Analytic Methodology
  This paper develops an analytic theory for the study of some Polya urns with random rules. The idea is to extend the isomorphism theorem in Flajolet et al. (2006), which connects deterministic balanced urns to a differential system for the generating function. The methodology is based upon adaptation of operators and use of a weighted probability generating function. Systems of differential equations are developed, and when they can be solved, they lead to characterization of the exact distributions underlying the urn evolution. We give a few illustrative examples. 
Basile Morcrette (LIP6, INRIA Rocquencourt), Hosam M. Mahmoud
math.CO cs.DM math.PR