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Introduction

In this chapter, we survey a number of areas of lexical semantics which are often refered to and used with some adaptations in NLP applications. One of the aims of this section is to provide the reader with a background of linguistic issues in lexical semantics so that he/she can have a better view of what the main definitions, the hypothesis, the foundations and the limitations of each area are. These linguistic issues are often not used directly in NLP systems and in the description of lexical resources, they are usually adapted in various degrees to make the descriptions e.g. more comprehensive, and better suited for the problem or the domain addressed.

The elements presented here are basic issues in lexical semantics and have in most cases an inter-theoretical perspective. They have been judged to be sufficiently stable to be presented here. They can therefore be used in a number of frameworks; they can also be integrated or combined with a large number of syntactic systems. A choice criterion has been that lexical semantic descriptions should be as easy to use as possible and non-ambiguous. They should also be as language independent as possible and easy to encode in a lexicon. It should be noted that we do not claim to be comprehensive, and the absence of a framework is certainly not an a priori judgement of its value. Lexical semantics is indeed a vast area with many ramifications, impossible to cover in such a document.

The areas surveyed here are the following:

For each area, a description of the main approaches is first given, followed by comparisons aimed at identifying basic notions and components. Then relations to other areas of lexical semantics are emphasized. Finally, as a form of pointer towards the two next chapters, indications are given on how lexical semantics data is encoded in lexical knowledge bases and used in large-size NL applications 4.

Lexical semantics being a very vast domain, it has not been possible to include every approach. Among the missing frameworks that we foresee to add in the future are the Mel'cuk functional system (mentioned in passing in some paragraphs), the Script/Frame systems, frame nets and recent developments in ontology description.



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Next: Lexical aspect Up: Linguistic aspects of lexical Previous: Linguistic aspects of lexical
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