  The Noisy-Or model is convenient for describing a class of uncertain
relationships in Bayesian networks [Pearl 1988]. Pearl describes the Noisy-Or
model for Boolean variables. Here we generalize the model to nary input and
output variables and to arbitrary functions other than the Boolean OR function.
This generalization is a useful modeling aid for construction of Bayesian
networks. We illustrate with some examples including digital circuit diagnosis
and network reliability analysis.
