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Treedy: A Heuristic for Counting and Sampling Subsets
Proceedings of the 29th Conference on Uncertainty in Artificial Intelligence, PMLR R11:184-192, 2013.
Abstract
Consider a collection of weighted subsets of a ground set N. Given a query subset Q of N, how fast can one (1) find the weighted sum over all subsets of Q, and (2) sample a sub- set of Q proportionally to the weights? We present a tree-based greedy heuristic, Treedy, that for a given positive tolerance d answers such counting and sampling queries to within a guaranteed relative error d and total vari- ation distance d, respectively. Experimen- tal results on artificial instances and in ap- plication to Bayesian structure discovery in Bayesian networks show that approximations yield dramatic savings in running time com- pared to exact computation, and that Treedy typically outperforms a previously proposed sorting-based heuristic.