Graphical representations of consensus belief

  • Authors:
  • David M. Pennock;Michael P. Wellman

  • Affiliations:
  • University of Michigan AI Laboratory, Ann Arbor, MI;University of Michigan AI Laboratory, Ann Arbor, MI

  • Venue:
  • UAI'99 Proceedings of the Fifteenth conference on Uncertainty in artificial intelligence
  • Year:
  • 1999

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Abstract

Graphical models based on conditional independence support concise encodings of the subjective belief of a single agent. A natural question is whether the consensus belief of a group of agents can be represented with equal parsimony. We prove, under relatively mild assumptions, that even if everyone agrees on a common graph topology, no method of combining beliefs can maintain that structure. Even weaker conditions rule out local aggregation within conditional probability tables. On a more positive note, we show that if probabilities are combined with the logarithmic opinion pool (LogOP), then commonly held Markov independencies are maintained. This suggests a straightforward procedure for constructing a consensus Markov network. We describe an algorithm for computing the LogOP with time complexity comparable to that of exact Bayesian inference.