16. The method as recited in claim 14 , wherein a subset of the logical expressions that are true is determined with computational effort proportional to a number of times the primitives are evaluated.
14. The method as recited in claim 13 , wherein the one or more directed acyclic graphs include at least one node associated with one of the primitives used in at least one of the logical expressions, a value of the one of the primitives being evaluated to reflect the current state of the model when the node is visited in traversing the one or more directed acyclic graphs.