We will now look at another class of exact inference algorithms based on message passing.
Message passing is a general mechanism, and there exist many variations of message passing algorithms. We shall look at a short snippet of the clique tree-message passing algorithm (which is sometimes called the junction tree algorithm too). Other versions of the message passing algorithm are used in approximate inference as well.
We initiate the discussion by clarifying some of the terms used.
A cluster graph is an arrangement of a network where groups of variables are placed in the cluster. It is similar to a factor where each cluster has a set of variables in its scope.
The message passing algorithm is all about passing messages between ...