text: Like any other logical theory, domain descriptions in reasoning about actions may evolve, and thus need revision methods to adequately accommodate new information about the behavior of actions. The present work is about changing action domain descriptions in propositional dynamic logic. Its contribution is threefold: first we revisit the semantics of action theory contraction that has been done in previous work, giving more robust operators that express minimal change based on a notion of distance between Kripke-models. Second we give algorithms for syntactical action theory contraction and establish their correctness w.r.t. our semantics. Finally we state postulates for action theory contraction and assess the behavior of our operators w.r.t. them. Moreover, we also address the revision counterpart of action theory change, showing that it benefits from our semantics for contraction.
  @cite_5: How can an intelligent agent update her knowledge base about an action domain, relative to some conditions (possibly obtained from earlier observations)? We study this question in a formal framework for reasoning about actions and change, in which the meaning of an action domain description can be represented by a directed graph whose nodes correspond to states and whose edges correspond to action occurrences. We define the update of an action domain description in this framework, and show among other results that a solution to this problem can be obtained by a divide-and-conquer approach in some cases. We also introduce methods to compute a solution and an approximate solution to this problem, and analyze the computational complexity of these problems. Finally, we discuss techniques to improve the quality of solutions.
  @cite_52: We study resolving conflicts between an action description and a set of conditions (possibly obtained from observations), in the context of action languages. In this formal framework, the meaning of an action description can be represented by a transition diagram---a directed graph whose nodes correspond to states and whose edges correspond to transitions describing action occurrences. This allows us to characterize conflicts by means of states and transitions of the given action description that violate some given conditions. We introduce a basic method to resolve such conflicts by modifying the action description, and discuss how the user can be supported in obtaining more preferred solutions. For that, we identify helpful questions the user may ask (e.g., which specific parts of the action description cause a conflict with some given condition), and we provide answers to them using properties of action descriptions and transition diagrams. Finally, we discuss the computational complexity of these questions in terms of related decision problems.
summary: The work by Eiter al @cite_5 @cite_52 is similar to ours in that they also propose a framework that is oriented to updating action laws. They mainly investigate the case where a new effect law is added to the description (and then has to be true in all models of the modified theory). This problem is the dual of contraction and is then closer to our definition of revision ( ).