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<Paper uid="W97-0801">
  <Title>Multilingual design of EuroWordNet Piek Vossen, University of Amsterdam</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> EuroWordNet is an EC-funded project (LE2-4003) that aims at building a multilingual database consisting of wordnets in several European languages (English, Dutch, Italian, and Spanish). Each language specific wordnet is structured along the same lines as WordNet (Miller90), i.e. synonyms are grouped in synsets, which in their turn are related by means of basic semantic relations. null The EuroWordNet database will as much as possible be built from available existing resources and databases with semantic information developed in various projects. This will not only be more cost-effective but will also make it possible to combine information from independently created resources, making the final database more consistent and reliable, while keeping the richness and diversity of the vocabularies of the different languages. For that purpose the language-specific wordnets will be stored as independent language-internal systems in a central lexical database while the equivalent word meanings across the languages will be linked to each other.</Paragraph>
    <Paragraph position="1"> The multilingual nature of this conceptual database raises methodological issues for its design and development. First there is the question of which architecture to adopt. We have considered four possible designs: a) Linking by pairs of languages.</Paragraph>
    <Paragraph position="2">  b) Linking through an structured artificial language c) Linking through one of the languages d) Linking through an non-structured index  The first option (a) is to pair-wise link the languages involved. This makes it possible to precisely establish the specific equivalence relation across pairs of languages, but it also multiplies the work by the number of languages to be linked. Furthermore, the addition of a new language will ask for the addition of new equivalence relations to all the other languages, with all the possible consequences. The second option (b) is to link the languages through an structured language-neutral inter-lingua. A language-independent conceptual system or structure may be represented in an efficient and accurate way but the challenge and difficulty is to achieve such a meta-lexicon, capable of supplying a satisfactory conceptual backbone to all the languages. A drawback from a methodological point of view is that new words that are added in one of the languages might call for a revision of a part of the language-independent network. As a third possibility the linking can be established through one of the languages. This resolves the inconveniences and difficulties of the former two options, but forces an excessive dependency on the lexical and conceptual structure of one of the languages involved. The last possibility (d) is to link through a non-structured list of concepts, which forms the superset of all concepts encountered in the different languages involved. This list does not satisfy any cognitive theory, because it is an unstructured index with unique identifiers for concepts that do not have any internal or language-independent structure. This has the advantage that it is not necessary to maintain a complex semantic structure that incorporates the complexity of all languages involved. Furthermore, the addition of a new language will minimally affect any of the existing wordnets or their equivalence relations to this index.</Paragraph>
    <Paragraph position="3"> For pragmatic reasons we have chosen design (d). An unstructured index as a linking device is most beneficial with respect to the effort needed for the development, maintenance, future expansion and reusability of the multilingual database. Of course the adopted architecture is not without its difficulties. These are especially crucial in the process of handling the index and creating tools for the developers to obtain a satisfactory result. Tasks such as identifying the right inter-hngual correspondence when a new synset is added in one language, or how to control the balance between the languages are good examples of issues that need to be resolved when this approach is taken.</Paragraph>
    <Paragraph position="4"> In this paper we will further explain the design of the database incorporating the unstructured multilingual index. The structure of this paper is then as follows: first we will describe the general architecture of the database with the different modules. In section 3 we will discuss how language-specific relations and complex-equivalence relations are stored. Finally, section 4 deals with the specific options to compare the wordnets and derive information on the equivalence relations and the differences in wordnet structure.</Paragraph>
  </Section>
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