tailieunhanh - Báo cáo khoa học: "A MODEL OF PLAN INFERENCE THAT DISTINGUISHES BETWEEN THE BELIEFS OF ACTORS AND OBSERVERS"

Existing models of plan inference (PI) in conversation have assumed that the agent whose plan is being inferred (the actor) and the agent drawing the inference (the observer) have identical beliefs about actions in the domain. I argue that this assumption often results in failure of both the PI process and the communicative process that PI is meant to support. In particular, it precludes the principled generation of appropriate responses to queries that arise from invalid plans. I describe a model of P1 that abandons this assumption. It rests on an analysis of plans as mental phenomena. Judgements that. | A MODEL OF PLAN INFERENCE THAT DISTINGUISHES BETWEEN THE BELIEFS OF ACTORS AND OBSERVERS Martha E. Pollack Artificial Intelligence Center and Center for the Study of Language and Information SRI International 333 Ravenswood Avenue Menlo Park CA 94025 ABSTRACT Existing models of plan inference PI in conversation have assumed that the agent whose plan is being inferred the actor and the agent drawing the inference the observer have identical beliefs about actions in the domain. I argue that this assumption often results in failure of both the PI process and the communicative process that PI is meant to support. In particular it precludes the principled generation of appropriate responses to queries that arise from invalid plans. I describe a model of PI that abandons this assumption. It rests on an analysis of plans as mental phenomena. Judgements that a plan is invalid are associated with particular discrepancies between the beliefs that the observer ascribes to the actor when the former believes that the latter has some plan and the beliefs that the observer herself holds. I show that the content of an appropriate response to a query is affected by the types of any such discrepancies of belief judged to be present in the plan inferred to underlie that query. The PI model described here has been implemented in SPIRIT a small demonstration system that answers questions about the domain of computer mail. INTRODUCTION The importance of plan inference PI in models of conversation has been widely noted in the computational-linguistics literature. Incorporating PI capabilities into systems that answer users questions has enabled such systems to handle indirect speech acts 13 supply more information than is actually requested in a query 2 provide helpful information in response to a yes no query answered in the negative 2 disambiguate requests 17 resolve certain forms of intersentential ellipsis 6 11 and handle such discourse phenomena as clarification subdialogues 11 and