Word Sense Disambiguation and Sense-Based NV Event Frame Identifier

29 Computational Linguistics and Chinese Language Processing Vol. 7, No. 1, February 2002, pp. 29-46  The Association for Computational Linguistics and Chinese Language Processing. Word Sense Disambiguation and Sense-Based NV Event Frame Identifier Jia-Lin Tsai*, Wen-Lian Hsu and Jeng-Woei Su Abstract Word sense is ambiguous in natural language processing (NLP). This phenomenon is particularly keen in cases involving noun-verb (NV) word-pairs. This paper describes a sense-based noun-verb event frame (NVEF) identifier that can be used to disambiguate word sense in Chinese sentences effectively. A knowledge representation system (the NVEF-KR tree) for the NVEF sense-pair identifier is also proposed. We use the word sense of Hownet, which is a Chinese-English bilingual knowledge-base dictionary. Our experiment showed that the NVEF identifier was able to achieve 74.8% accuracy for the test sentences studied based only on NVEF sense-pair knowledge. By applying the techniques of longest syllabic NVEF-word-pair first and exclusion word checking, the sense accuracy for the same test sentences could be further improved to 93.7%. There were four major reasons for the incorrect cases: (1) lack of a bottom-up tagger, (2) lack of non-NVEF knowledge, (3) inadequate word segmentation, and (4) lack of a multi-NVEF analyzer. If these four problems could be resolved, the accuracy would reach 98.9%. The results of this study indicate that NVEF sense-pair knowledge is effective for word sense disambiguation and is likely to be important for general NLP. Keywords: word sense disambiguation, event frame, top-down identifier, Hownet 1. Introduction Word sense disambiguation (WSD) has been a pervasive problem in natural language processing (NLP) since 1949 [Weaver 1949]. Word sense ambiguity (or lexical ambiguity), is generally classified into two types: syntactic and semantic ambiguity [Small et al. 1988, Krovetz et al. 1992]. Syntactic ambiguity is caused by differences in syntactic categories (e.g. * Institute of Information Science, Academia Sinica, Nankang, Taipei, Taiwan, R.O.C. E-mail: {tsaijl,hsu,raycs}@iis.sinica.edu.tw 30 J. L. Tsai et al. “play” can occur as a noun or verb). Semantic ambiguity is caused by homonymy (e.g. “bank” in “to put money in a bank,” “the bank of a river”) or polysemy (e.g. “face” in “human face,” “face of a clock”). Although many approaches have been adopted to disambiguate word sense, algorithms for word sense determination still are not reliable [Krovetz et al. 1992, Resnik et al. 2000]. Human beings usually can disambiguate word sense by using additional information from the speaker, the writer or the context. When out-of-context (or out-of-sentence) information is not symbolized and processed in the computer, WSD either becomes very difficult or, sometimes, impossible. Therefore, it is crucial to investigate what kind of knowledge is useful for WSD [Krovetz et al. 1992]. According to a study in cognitive science [Choueka et al. 1983], people often disambiguate word sense using only a few other words in a given context (frequently only one additional word). Thus, the relationships between one word and others can be effectively used to resolve ambiguity. Furthermore, from [Small et al. 1988, Krovetz et al. 1992, Resnik et al. 2000], most ambiguities …

Content truncated to 500 words