Consistency of Action Descriptions

As a contribution to the metatheory of reasoning about actions, we present some characteristics of the consistency of action theories. Three levels of consistency are investigated for the evaluation of action descriptions: uniform consistency, consistency of formulas and regional consistency. The first two provide an intuitive resolution of problems of explanation conflicts and fluent dependency. The concept of regional consistency provides for a measure of ramification. A highly expressive form of action descriptions, the normal form, is introduced to facilitate this analysis. The relative satisfiability of the situation calculus is generalized to accommodate non-deterministic effects and ramifications.