Dynamic Jointrees

TL;DR

This paper introduces a dynamic reconfiguration method for jointrees in belief networks, enabling more efficient probabilistic query processing by adapting to changing queries and reusing previous computations.

Contribution

It proposes a novel, efficient approach for dynamically reconfiguring jointrees based on a non-classical definition, improving computational savings for changing queries.

Findings

Significant savings over static jointrees when queries change substantially.

Reconfiguration reuses previous computations, enhancing efficiency.

Method maintains jointree relevance after network pruning.

Abstract

It is well known that one can ignore parts of a belief network when computing answers to certain probabilistic queries. It is also well known that the ignorable parts (if any) depend on the specific query of interest and, therefore, may change as the query changes. Algorithms based on jointrees, however, do not seem to take computational advantage of these facts given that they typically construct jointrees for worst-case queries; that is, queries for which every part of the belief network is considered relevant. To address this limitation, we propose in this paper a method for reconfiguring jointrees dynamically as the query changes. The reconfiguration process aims at maintaining a jointree which corresponds to the underlying belief network after it has been pruned given the current query. Our reconfiguration method is marked by three characteristics: (a) it is based on a non-classical definition of jointrees; (b) it is relatively efficient; and (c) it can reuse some of the computations performed before a jointree is reconfigured. We present preliminary experimental results which demonstrate significant savings over using static jointrees when query changes are considerable.