Marginalizing and conditioning in graphical models (Q1860998)

The author introduces the class of MC graphs and shows that it is closed under the operations of marginalizing over a certain subset of vertices, or conditioning on a subset of other vertices. The present paper addresses the marginalization and conditioning problem for a large class of graphs, containing at least all undirected graphs and all directional graphs. Directional graphs are important, since they occur as path diagrams in Gaussian linear structural equation systems.