机器学习之noisy or model

What is a Noisy-OR Model I am interested with the paper "Noisy-OR Component Analysis and its Application to Link Analysis" published by Tomas Singliar and Milos Hauskrecht on JMLR 7 (2006). A very preliminary prerequisite to understand this paper is to know the "noisy-or" model. However, it seems that noisy-or is an old topic and no much can be found via Google. Fortunately, I got a very brief description from an old paper "Possibility theory and the generalized Noisy OR model". Snapshotting the section on Noisy OR as an image as attached:

 属性            大小     日期    时间   名称
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     目录           0  2011-03-06 15:51  New folder\
     文件      536433  2011-01-04 00:23  New folder\approximating noisy or by naiive bayes.pdf
     文件      246553  2011-01-04 00:03  New folder\noisy or classifier.pdf
     文件     1403472  2011-01-04 00:05  New folder\solving noisy optimization by qp.pdf
     文件       43846  2010-12-12 22:17  noisy-or.png
     文件      130388  2010-12-12 23:40  Possibility theory and the generalized Noisy OR model.pdf
     文件      652924  2010-12-13 00:08  S4-Noisy Or Gate.pptx