Carnegie Mellon University
Learning Thin Junction Trees via Graph Cuts

Dafna Shahaf, Anton Chechetka, and Carlos Ernesto Guestrin
Artificial Intelligence and Statistics (AISTATS), April, 2009.

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Structure learning algorithms usually focus on the compactness of the learned model. However, for general compact models, both exact and approximate inference are still NP-hard. Therefore, the focus only on compactness leads to learning models that require approximate inference techniques, thus reducing their prediction quality. In this paper, we propose a method for learning an attractive class of models: bounded-treewidth junction trees, which permit both compact representation of probability distributions and efficient exact inference. Using Bethe approximation of the likelihood, we transform the problem of finding a good junction tree separator into a minimum cut problem on a weighted graph. Using the graph cut intuition, we present an efficient algorithm with theoretical guarantees for finding good separators, which we recursively apply to obtain a thin junction tree. Our extensive empirical evaluation demonstrates the benefit of applying exact inference using our models to answer queries. We also extend our technique to learning low tree-width conditional random fields, and demonstrate significant improvements over state of the art block-L1 regularization techniques.

Sponsor: NSF, ARO

Text Reference
Dafna Shahaf, Anton Chechetka, and Carlos Ernesto Guestrin, "Learning Thin Junction Trees via Graph Cuts," Artificial Intelligence and Statistics (AISTATS), April, 2009.

BibTeX Reference
   author = "Dafna Shahaf and Anton Chechetka and Carlos Ernesto Guestrin",
   title = "Learning Thin Junction Trees via Graph Cuts",
   booktitle = "Artificial Intelligence and Statistics (AISTATS)",
   month = "April",
   year = "2009",