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Unsupervised Learning of Noisy-OR Bayesian Networks
Proceedings of the 29th Conference on Uncertainty in Artificial Intelligence, PMLR R11:422-431, 2013.
Abstract
This paper considers the problem of learn- ing the parameters in Bayesian networks of discrete variables with known structure and hidden variables. Previous approaches in these settings typically use expectation maximization; when the network has high treewidth, the required expectations might be approximated using Monte Carlo or vari- ational methods. We show how to avoid inference altogether during learning by giv- ing a polynomial-time algorithm based on the method-of-moments, building upon re- cent work on learning discrete-valued mix- ture models. In particular, we show how to learn the parameters for a family of bipartite noisy-or Bayesian networks. In our experi- mental results, we demonstrate an applica- tion of our algorithm to learning QMR-DT, a large Bayesian network used for medical di- agnosis. We show that it is possible to fully learn the parameters of QMR-DT even when only the findings are observed in the training data (ground truth diseases unknown).