Inference in Bayesian Networks

How can one infer the (probabilities of) values of one or more network variables, given observed values of others?

• Bayes net contains all information needed for this inference
• If only one variable with unknown value, easy to infer it
• In general case, problem is NP hard

In practice, can succeed in many cases

• Exact inference methods work well for some network structures
• Monte Carlo methods ``simulate'' the network randomly to calculate approximate solutions