## Random Allocations and Urn Models

My interest on random allocations dates from studies on database performances in the 80s.
Some results deal with identifying classes of models (often related to database modelization, or to a learning problem) that are amenable to a uniform treatment. They often lead to so-called "occupancy urn models", i.e. models where balls are thrown into a sequence of urns and the question is, e.g., the distribution of the number of empty urns. Some of these results are static, some are « semi-dynamic » in the sense that queries and insertions, but not deletions, are allowed, and some are fully dynamic and allow for deletions.

Some years ago I went back to allocation models, driven by the need to
analyze some random generation algorithms, for which "waiting-time models" turned out to be well-suited:

- analyzing the performance of an algorithm for random
generation of Hadamard product leads to a boys-and-girls birthday
problem (with O. Bodini and O. Roussel, who both were then at Paris 6).

- a random generation algorithm for ARN sequences leads to a Coupon Collector model with unequal probabilities (with Y. Ponty at LIX).

List of publications