Forget It !

We encountered the need for a theory of forgetting in our work on Cognitive Robotics.1 In our effort to control an autonomous robot, we imagine the robot has a knowledge base representing the initial world state. As the robot performs actions, she needs to bring the knowledge base up to date. To do so, she needs to forget about all the facts that are no longer true, and in such a way that this will not affect any of her possible future actions (Lin and Reiter [3; 3]). This paper describes in general terms the particular forms of forgetting used in (Lin and Reiter [3; 3]). Specifically, we propose a logical theory to account for: forgetting about a fact (forget that John is a student), and forgetting about a relation (forget the student relation). We then apply our notion of forgetting in defining various notion of relevance.