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<Paper uid="A97-1021">
  <Title>Large-Scale Acquisition of LCS-Based Lexicons for Foreign Language Tutoring</Title>
  <Section position="8" start_page="143" end_page="144" type="concl">
    <SectionTitle>
6 Limitations and Conclusions
</SectionTitle>
    <Paragraph position="0"> We have described techniques for automatic construction of dictionaries for use in large-scale FLT. The dictionaries are based on a language-independent representation called lexical conceptual structure (LCS). Significant enhancements to LCS-based tutoring could be achieved by combining this representation with a mechanism for handling issues related to discourse and pragmatics. For example, Mthough the LCS processor is capable of determining that the phrase in the trash partially matches the answer to Where did John put the book?, a pragmatic component would be required to determine that this answer is (perhaps) more appropriate than the full answer, He put the book in the trash. Representing conversational context and dynamic context updating (Traum et al., 1996; Haller, 1996; DiEugenio and Webber, 1996) would provide a fl'amework for this type of response &amp;quot;relaxation.&amp;quot; Along SWe have defined approximately 100 such mappings per language. For example, the mapping produces the following primitive representations for the English word to: (to loc (at loc)), (to poss (at poss)), (to temp (at temp)), (toward loc (at loc)), (toward poss (at poss)). We have similar mappings defined in Arabic and Spanish. For example, the following primitive representations are produced for the Spanish word a: (at loc), (to loc (at loc)), (to poss (at poss)), (toward loc (at lot)).</Paragraph>
    <Paragraph position="1">  these same lines, a pragmatic component could provide a mechanism for det, ermining that certain fully matched responses (e.g., John hurled the book inlo the trash) are not. as &amp;quot;realistic sounding&amp;quot; as partially matched alternatives.</Paragraph>
    <Paragraph position="2"> Initially, LEXICALL was designed to support the development of LCS's for English only; however, the same techniques can be used for nmltilingual acquisition. As the lexicon coverage for other languages expands, it, is expected that our acquisition techniques will help further in the cross-linguistic investigation of the relationship between Levin's verb classes and the basic meaning components in the LCS represent, ation. In addition, it is expected that verbs in the same Levin class may have finer distinctions than what we have specified in the current LCS templates.</Paragraph>
    <Paragraph position="3"> We view the importation of LCS's from the English LCS database into Arabic and Spanish as a first, approxin~ation to the development of complete lexicons for these languages. The results have been hand-checked by native speakers using the class/grid/lexeme format (which is much easier to check than the flfily expanded LCS's). The lexical verification process took only two weeks by the native speakers. We estimate that, it would take at least 6 months to build such a lexicon from scratch (by human recall and data. entry alone), and in such a case, the potential for error would be a.t least twice as high.</Paragraph>
    <Paragraph position="4"> One important benefit of using the Levin classification as the basis of our program is that, once the mapping between verb classes and LCS representations has been established, we can acquire the LCS representation for a new verb (i.e., one not in Levin) simply by associating it. with one of the 191 classes. We see our approach as a first step toward compression of lexical entries in that it allows lexicons to be stored in terms of the more condensed class/grid/lexeme specifications; these can expanded online, as needed, during sentence processing in the NLP application.</Paragraph>
    <Paragraph position="5"> We conclude that, while human intervention is necessary for the acquisition of class/grid information, this intervention is virtually eliminated fi'om the LCS construction process because of our provision of a lnapping between semantic classes and primitive meaning components.</Paragraph>
  </Section>
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