Bernal S D_2010.pdf - University of Plymouth

3.3. DEFINITION AND MATHEMATICAL FORMULATION
and top-down causal evidence, 7r(jr), as shown in Equation (3.18). The A and n symbols (greek
letter for / and p) are chosen because the terms are derived from the likelihood and prior terms,
respectively, in the Bayes theorem (Equation (3.8)).
To understand how information from several descendants is combined at node X. we partition
the set C;^ into disjoint subsets, one for each child of X, For example, for the graph in Figure 3.4,
if X is not instantiated, we can write e^ —^xci ^^xci^--^^XCM- yi