An Overview of Distributed Belief Networks in Engineering Systems

This paper provides an overview of distributed belief networks and how they can model engineering systems. In extending the usual single-processor computational model to multiple processors, several interesting problems arise, which must be solved for the successful implementation of a distributed belief network. In keeping with the distributed computational model, no single processor has information about the structure of the entire distributed belief network , and inferences are to be computed using only local quantities. However, this leads to diiculties (which have not yet been resolved) when there are loops in the distributed belief network which contain nodes in two or more component networks. Also, temporal dependencies in one network lead to temporal dependencies in any other network connected to some of its variables; this may lead to intractable dependencies, especially if some of the dependencies involve diierent time scales. While these problems of induced dependencies have only been identiied, and not resolved, progress has been been made in other areas. A general policy is proposed for publishing information as belief networks. A modeling language for the representation of distributed belief networks has been devised, and software has been implemented to compile the modeling language and carry out inferences. The paper concludes with some notes on the application of distributed belief networks to HVAC systems.