tailieunhanh - Báo cáo khoa học: "What's Necessary to Hide?: Modeling Action Verbs"

This paper considers what types of knowledge one must possess in order to reason about actions. Rather than concentrating on how actions are performed, as is done in the problem-solving literature, it examines the set of conditions under which an action can be said to have occurred. In other words, if one is told that action A occurred, what can be inferred about the state of the world? In particular, if the representation can define such conditions, it must have good models of time, belief, and intention. . | What s Necessary to Hide Modeling Action Verbs James F. Allen Computer Science Department University of Rochester Rochester NY 14627 Abstract This paper considers what types of knowledge one must possess in order to reason about actions. Rather than concentfating on how actions are performed as is done in the problem-solving literature it examines the set of conditions under which an action can be said to have occurred. In other words if one is told that action A occurred what can be inferred about the state of the world In particular if the representation can define such conditions it must have good models of time belief and intention. This paper discusses these issues and suggests a formalism in which general actions and events can be defined. Throughout the action of hiding a book from someone is used as a motivating example. 1. Introduction This paper suggests a formulation of events and actions that seems powerful enough to define a wide range of event and action verbs in English. This problem is interesting for two reasons. The first is that such a model is necessary to express the meaning of many sentences. The second is to analyze the language production and comprehension processes themselves as purposeful action. This was suggested some time ago by Bruce 1975 and Schmidt 1975 . Detailed proposals have been implemented recently for some aspects of language production Cohen 1978 and comprehension Allen 1979 As interest in these methods grows . see Grosz 1979 Brachman 1979 the inadequacy of existing action models becomes increasingly obvious. The formalism for actions used in most natural language understanding systems is based on case grammar. Each action is represented by a set of assertions about the semantic roles the noun phrases play with respect to the verb. Such a formalism is a start but does not explain how to represent what an action actually signifies. If one is told that a certain action occurred what does one know about how the world changed