Decision Systems and Artificial Intelligence Laboratory - Research



Department of Electrical Engineering and Computer Science
University of Wisconsin Milwaukee.



- BNG -
Bayesian Network Generator

BNG is a tools for constructing structurally minimal Bayesian Networks from universally quantified probability logic statements with optional context contrainsts.


Investigators

Current Status
BNG is a system for knowledge-based construction of Bayesian networks. A class of Bayesian networks is specified with a knowledge base of rules. Rules may contain universally quantified temporal and non-temporal variables, as well as context constraints. Context constraints are deterministic information used to index probabilistic relations. Given a knowledge base, a set of context information, some evidence, and a query, BNG constructs the structurally minimal Bayesian network to compute the posterior probability of the query given the evidence within the given context. This is done by first constructing the network, as indexed by the context and then performing fast d-separation based pruning. The pruning is made efficient by incorporating it in the network construction process.

BNG provides both representational and computational advantages over the use of traditional Bayesian networks. The incorporation of quantified variables in the knowledge base allows the representation of information not expressible in traditional Bayesian networks. Because only a small portion of a large probabilistic model may be relevant to the computation of a particular posterior probability, use of BNG can result in significant computational savings. These savings can be particularly large with temporal Bayesian networks.

The knowledge base representation language has a declarative semantics and the network construction algorithm has been proven sound and complete.

BNG is written in CommonLisp and interfaces to IDEAL. A user manual and example files are provided.



Software

Publications
  1. Ngo L, Haddawy P. Answering queries from context-sensitive probabilistic knowledge bases. Submitted to Theoretical Computer Science special issue on Uncertainty in Databases and Deductive Systems, March, 1995. [ Compressed PostScript]

  2. Ngo L, Haddawy P, Helwig J. A theoretical framework for context-sensitive temporal probability model construction with application to plan projection. In: Proceedings UAI-95, pp. 419-426, August 1995. [ Compressed PostScript]

  3. Haddawy P, Helwig J, Ngo L, Krieger R. Clinical simulation using context-sensitive temporal probability models. Proceedings of the 19th Annual Symposium on Computer Applications in Medical Care 1995:203-207. [ Compressed PostScript]

  4. Haddawy P, Generating Bayesian networks from probability logic knowledge bases. In: Proceedings UAI-94, pp. 262-269, July 1994. [ Compressed PostScript]