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Discrete Sampling using Semigradient-based Product Mixtures
Proceedings of the 34th Conference on Uncertainty in Artificial Intelligence, PMLR R16:228-236, 2018.
Abstract
We consider the problem of inference in dis- crete probabilistic models, that is, distributions over subsets of a finite ground set. These encompass a range of well-known models in machine learning, such as determinantal point processes and Ising models. Locally-moving Markov chain Monte Carlo algorithms, such as the Gibbs sampler, are commonly used for inference in such models, but their conver- gence is, at times, prohibitively slow. This is often caused by state-space bottlenecks that greatly hinder the movement of such samplers. We propose a novel sampling strategy that uses a specific mixture of product distributions to propose global moves and, thus, acceler- ate convergence. Furthermore, we show how to construct such a mixture using semigradi- ent information. We illustrate the effective- ness of combining our sampler with existing ones, both theoretically on an example model, as well as practically on three models learned from real-world data sets.