A preferential semantics for causal reasoning about action

One of the principal concerns in the research area of Reasoning about Action is determining the ramifications of actions in changing environments. A particular tendency emerging in recent literature endorses the explicit incorporation of causal knowledge in logic-based action theories. It is argued that causal extensions not only enhance the expressive power of theories of action, but may also provide more concise and intuitive representations. This paper investigates semantics for causal reasoning about action and change. It does so by exploring the role of several fundamental underlying principles, such as the Principle of Minimal Change and the Principle of Causal Change. This work culminates in a general unifying semantics for a class of action theories represented by a number of recent and influential approaches - in particular, the causal relationship approach of Thielscher and the causal systems with fixed-points suggested by McCain and Turner. The unifying augmented preferential semantics, emerging as a result of this study, captures both Principles of Change and shows their clear and distinct roles.