Ramification Constraints Revisited

We present a method to derive a solution to the combined frame and ramification problems for certain classes of theories of action written in the situation calculus. The theories of action considered include the causal laws of the domain, in the form of a set of effect axioms, as well as a set of ramification state constraints. The causal laws state the direct effects that actions have on the world, while ramification state constraints allow one to derive indirect effects of actions on the domain. To solve the combined frame and ramification problems, the causal laws and ramification state constraints are replaced by a set of successor state axioms. Given a state of the world, these axioms uniquely determine the truth value of dynamic properties after an action is performed. In this article, we extend previous work by formulating an approach for the mechanical generation of these successor state axioms. The approach works for classes of syntactically restricted sets of ramification state constraints. Furthermore, the approach is also limited by the applicability of the monotonic solution to the frame problem to deterministic domains.