Adaptive Belief Propagation

Graphical models are widely used in inference problems. In practice, one may construct a single large-scale model to explain a phenomenon of interest, which may be utilized in a variety of settings. The latent variables of interest, which can differ in each setting, may only represent a small subset of all variables. The marginals of variables of interest may change after the addition of measurements at different time points. In such adaptive settings, naı̈ve algorithms, such as standard belief propagation (BP), may utilize many unnecessary computations by propagating messages over the entire graph. Here, we formulate an efficient inference procedure, termed adaptive BP (AdaBP), suitable for adaptive inference settings. We show that it gives exact results for trees in discrete and Gaussian Markov Random Fields (MRFs), and provide an extension to Gaussian loopy graphs. We also provide extensions on finding the most likely sequence of the entire latent graph. Lastly, we compare the proposed method to standard BP and to that of (Sümer et al., 2011), which tackles the same problem. We show in synthetic and real experiments that it outperforms standard BP by orders of magnitude and explore the settings that it is advantageous over (Sümer et al., 2011).