Accumulation of Lexical Sets: Acquisition of Dictionary Resources and Production of New Lexical Sets

Accumulation of Lexical Sets: Acquisition of Dictionary Resources and Production of New Lexical Sets DOAN-NGUYEN Hai GETA - CLIPS - IMAG BP 53, 38041 Grenoble, France Fax: (33) 4 76 51 44 05 - Tel: (33) 4 76 63 59 76 - E-mail: Hai.Doan-Nguyen@imag.fr Abstract This paper presents our work on accumulation of lexical sets which includes acquisition of dictionary resources and production of new lexical sets from this. The method for the acquisition, using a context-free syntax-directed translator and text modification techniques, proves easy-to-use, flexible, and efficient. Categories of production are analyzed, and basic operations are proposed which make up a formalism for specifying and doing production. About 1.7 million lexical units were acquired and produced from dictionaries of various ~pes and complexities. The paper also proposes a combinatorial and dynamic organization for lexical systems, which is based on the notion of virtual accumulation and the abstraction levels of lexical sets. Keywords: dictionary resources, lexical acquisition, lexical production, lexical accumulation, computational lexicography. Introduction Acquisition and exploitation of dictionary resources (DRs) (machine-readable, on-line dictionaries, computational lexicons, etc) have long been recognized as important and difficult problems. Although there was a lot of work on DR acquisition, such as Byrd & al (1987), Neff & Boguraev (1989), Bl~isi & Koch (1992), etc, it is still desirable to develop general, powerful, and easy-to-use methods and tools for this. Production of new dictionaries, even only crude drafts, from available ones, has been much less treated, and it seems that no general computational framework has been proposed (see eg, Byrd & al (1987), Tanaka & Umemura (1994), Don" & al (1995)). This paper deals with two problems: acquiring textual DRs by converting them into structured forms, and producing new lexical sets from those acquired. These two can be considered as two main activities of a more general notion: the accumulation of lexical sets. The term "lexical set" (LS) is used here to be a generic term for more specific ones such as "lexicon", "dictionary", and "lexical database". Lexical data accumulated will be represented as objects of the Common Lisp Object System (CLOS) (Steel 1990). This object-oriented high- level programming environment facilitates any further manipulations on them, such as presentation (eg in formatted text), exchange (eg in SGML), database access, and production of new lexical structures, etc; the CLOS object form is thus a convenient pivot form for storing lexical units. This environment also helps us develop our methods and tools easily and efficiently. In this paper, we will also discuss some other relevant issues: complexity measures for dictionaries, heuristic decisions in acquisition, the idea of virtual accumulation, abstraction levels on LSs, and a design for organization and exploitation of large lexical systems based on the notions of accumulation. 1 Acquisition Our method combines the use of a context-free syntax-directed translator and text modification techniques. 1.1 A syntax-directed translator for acquisition Transforming a DR into a structured form comprises parsing the source text and building the output structures. Our approach is different from those of …

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