Lazy evaluation in penniless propagation over join trees

Abstract

AbstractIn this paper, we investigate the application of the ideas behind Lazy propagation to the Penniless propagation scheme. Probabilistic potentials attached to the messages and the nodes of the join tree are represented in a factorized way as a product of (approximate) probability trees, and the combination operations are postponed until they are compulsory for the deletion of a variable. We tested two variations of the basic Lazy scheme: One is based on keeping a hash table for the operations with probabilistic potentials that are carried out more than once during the propagation, to avoid repeating computations; the other uses a heuristic method to determine the order of the operations when combining a set of potentials. © 2002 Wiley Periodicals, Inc.