Corpus-Based Approach for Nominal Compound Analysis for Korean Based on Linguistic and Statistical Information

Corpus-Based Approach for Nominal Compound Analysis for Korean Based on Linguistic and Statistical Information Juntae Yoon* jtyoon@linc.cis.upenn.edu IRCS Univ. of Pennsylvania Philladelphia, PA 19104~ USA Key-Sun Choi kschoi@world.kaist.ac.kr KORTERM Dept. of Computer Science KAIST~ Taejon 305-701~ Korea Mansuk Song mssong@december.yonsei.ac.kr Dept. of Computer Science Yonsei Univ. Seoul 120-749, Korea Abstract Accurate nominal compound analysis is cru- cial for in application of natural language pro- cessing such as information retrieval and ex- traction as well as nominal compound inter- pretation. I,n the nominal compound analysis area, some corpus-based approaches have re- ported successful results by using statistal co- occurrences of nouns. But a nominal compound often has the similar structure to a simple sen- tence, e.g. the complement-predicate structure, as well as representing compound meaning with several nouns combined. Due to the grammar- ical characteristics of nominal compounds, the fi'amework based only on statistcal association between nouns often fails to analyze their struc- tures accurately, especially in Korean. This pc- per presents a new model for Korean nominal compound analysis on the basis of linguistic and statistical knowledge. The syntactic relations often have an effect on determining the struc- ture of nominal compounds, and we analyzed 40 million word corpus in order to acquire syn- tactic and s-tatistical knowledge. The structure of a nominal compound is analyzed based on the linguistic lexical information extracted. By experiments, it is shown that our method is ef- fective for accurate analysis of Korean nominal compounds. 1 Introduction Nominal compound analysis is one of crucial issues that have been continuously studied by computational and theoretical linguists. Many linguists have dealt with nonlinal compounds in view of semantic interpretation, and tried to explain how nominal compounds are semanti- This work was partially supported by a KOSEF's post- doctoral fellowship grant. cally interpreted (Levi, 1978; Selkirk, 1982). In the field of natural language processing, various computational models have been established for syntactic analysis and semantic interpretation of nominal compounds (Finin, 1980; McDon- ald, 1982; Arens ct al. , 1987; Pustejovsky et al. , 1993; Kobayasi et al. , 1994; Van- derwerde, 1994; Lauer, 1995). Recently it has been shown that noun phrase analysis is effec- rive for the improvement of the application of natural language processing such as information retrieval (Zhai, 1997). Parsing nominal compound is a basic step for ~11 problems related to it. From a brack- eting point of view, structural ambiguity is also a main problem in nominal compomld analysis like in other parsing problems. Re(:ent works have shown that the corpus-b;~sed approach for nominal compound analysis makes a good re- sult to resolve the ambiguities (Fustcjovsky et al. , 1993; Kobayasi et al. , 1994; Lauer, 1995; Zhai, 1997). Lauer (1995) has compared two diffbrent models of corpus-based approaches fbr nomi- nal compound analysis. One was called as the adjacency model which was inspired by (Puste- jovsky et al. , 1993), and the other was re- ferred to as the dependency model which was presented by Kobayasi ~t al. (1994) 2 and Lauer …

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