Variational Methods for Graphical Models ∗

∗a summary of [JGJS99] †pat@student.ethz.ch problem [Coo87]. Thus, as in other areas, the research focus has shifted from finding exact algorithms, towards finding good approximation schemes. Nevertheless there are important special instances of graphical models, e.g. trees, where exact algorithms are efficient. And, as we will see, even in the framework of variational methods, we want to use exact algorithms.