Markov equivalence for ancestral graphs. (English) Zbl 1178.68574

Summary: Ancestral graphs can encode conditional independence relations that arise in Directed Acyclic Graph (DAG) models with latent and selection variables. However, for any ancestral graph, there may be several other graphs to which it is Markov equivalent. We state and prove conditions under which two maximal ancestral graphs are Markov equivalent to each other, thereby extending analogous results for DAGs given by other authors. These conditions lead to an algorithm for determining Markov equivalence that runs in time that is polynomial in the number of vertices in the graph.


68T30 Knowledge representation
05C75 Structural characterization of families of graphs
68T37 Reasoning under uncertainty in the context of artificial intelligence


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