Bayesian networks provide an elegant formalism for representing and reasoning about uncertainty using probability theory. They are a probabilistic extension of propositional logic and, hence, inherit some of the limitations of propositional logic, such as the difficulties to represent objects and relations. We introduce a generalization of Bayesian networks, called Bayesian logic programs, to overcome these limitations. In order to represent objects and relations it combines Bayesian networks with definite clause logic by establishing a one-to-one mapping between ground atoms and random variables. We show that Bayesian logic programs combine the advantages of both definite clause logic and Bayesian networks. This includes the separation of quantitative and qualitative aspects of the model. Furthermore, Bayesian logic programs generalize both Bayesian networks as well as logic programs. So, many ideas developed in both areas carry over.Proposition 5.4. Let B be a Bayesian logic program, N its (possibly infinite) Bayesian network and X 1 , . . . , X m , m > 0, nodes of N . The support network N (X 1 , . . . , X m ) is the graph union G of all single support networks N (X i ).Proof. First, we show that N (X 1 , . . . , X m ) and G have the same set of nodes. The support network N (X 1 , . . . , X m ) has per definitionem a node A if and only if A is influencing a X i ∈ {X 1 , . . . , X m }. But, A is influencing a X i ∈ {X 1 , . . . , X m } if and only if A is a node in N (X i ), i.e. A is a node in G.Now, we prove that N (X 1 , . . . , X m ) and G have the same set of edges. A support network N (X 1 , . . . , X m ) has an edge E from a node A i to a node A j if and only if (1) both nodes, A i and A j are influencing a X k ∈ {X 1 , . . . , X m } and are therefore in N (X k ), and (2) the edge E is in N . Per definitionem of a support network this is if an only if the edge E is in N (X k ), i.e. E is an edge in G.
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