Then the simple regression model described in the preceding section, extended to include alignment and constraint variables, has the form of the factor graph shown in Figure 4.
the joint distribution p(T, V) is the product of four groups of factors: Alignment factors ψ ta , which use a log-linear model to score neighboring pairs of factors with a feature function ϕ a : Constraint factors ψ tc , which map text features onto constraint values: Prediction factors ψ acv which encourage predicted constraints and path features to agree: A global factor ψ a * (A 1 , A 2 , • • • ) which places an arbitrary combinatorial constraint on the alignment.