tailieunhanh - Báo cáo khoa học: "Flexible Parsing"

When people use natural language in natural settings, they often use it ungrammatically, rnisSing out or repeating words, breaking-oil and restarting, speaking in Iragments, etc Their human listeners are usually able to cope with these deviations with little difficulty. If a computer system wislles tc accept natural language input from its users on a routine basis, it must display a similar indifference. In this paper, we outline a set of parsing flexibiiilies that :',uch a system should provide. We go, on to describe FlexP. a bottom-up pattern-matching parser that we have designed and implemented to provide these flexibilities for. | Flexible Parsing Phil Hayes and George Mouradian Computer Science Department. Carnegie-Mellon University Pittsburgh. PA 15213 USA Abstract When people use natural language in natural settings they often use it ungrammatically missing out or repeating words breaking-off and restarting speaking in fragments etc. Their human listeners are usually able to cope with these deviations with little difficulty. If a computer system wishes tc accept natural language input from its users on a routine basis it must display a similar indifference. In this paper we outline a set of parsing flexibilities that such a system should provide. We go. on to describe FlexP. a bottom-up pattern-matching parser that we have designed and implemented to provide these flexibilities for restricted natural language input to a limited-domain computer system. 1. The Importance of Flexible Parsing When people use natural language in natural conversation they often do not respect grammatical niceties. Instead of speaking sequences of grammatically well-formed and complete sentences people often miss out or repeat words or phrases break off what they are saying and rephrase or replace it. speak in fragments or use otherwise incorrect grammar. The following example conversation involves a number of these grammatical deviations A I want. can you send a memo a message to to Smith Is that John or John Smith or Jim Smith A Jim Instead of being unable or refusing to parse such ungrammaticality human listeners are generally unperturbed by it. Neither participant in the above example for instance would have any difficulty in following the conversation. If computers are ever to converse naturally with humans they must be able to parse their input as flexibly and robustly ns humans do. While considerable advances have been made in recent years in applied natural language processing few of the systems that have been constructed have pakl sufficient attention to lhe kinds of deviation that will inevitably occur