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Faster Perfect Sampling of Bayesian Network Structures
Proceedings of the Fortieth Conference on Uncertainty in Artificial Intelligence, PMLR 244:1558-1568, 2024.
Abstract
Bayesian inference of a Bayesian network structure amounts to averaging over directed acyclic graphs (DAGs) on a given set of n variables, each DAG weighted by its posterior probability. In practice, save some special inference tasks, one averages over a sample of DAGs generated perfectly or approximately from the posterior. For the hard problem of perfect sampling, we give an algorithm that runs in O(2.829n) expected time, getting below O(3n) for the first time. Our algorithm reduces the problem into two smaller sampling problems whose outputs are combined; followed by a simple rejection step, perfect samples are obtained. Subsequent samples can be generated considerably faster. Empirically, we observe speedups of several orders of magnitude over the state of the art.