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<Paper uid="W98-0713">
  <Title>I I I ! I ! I I I ! I I I I I i I I Lexical Acquisition with WordNet and the Mikrokosmos Ontology</Title>
  <Section position="3" start_page="95" end_page="96" type="intro">
    <SectionTitle>
2 Background and Examples
</SectionTitle>
    <Paragraph position="0"> In Mikrokosmos, most of the language-neutral information is stored in the ontology. Each concept is represented by a rich flame structure, which allows for numerous links among the concepts. For instance, it includes theme and instrument relations, as well as the more usual /s-a and set-membership relations; the ontology also contains selectional restrictions on case roles. In contrast, the lexicon contains just the information needed to realize a concept in a given language (Onyshkevych and Nirenburg, 1994). It will contain the usual information about morphology and syntax; but, most of the semantics will be defined in terms of a concept from the ontology. Therefore, the semantics for the lexicon entry might just be a direct mapping to the associated</Paragraph>
    <Paragraph position="2"> (def &amp;quot;a copy of a written work or composition that has been published&amp;quot;) (ex &amp;quot;I just read a good book on economics&amp;quot;) (cro~-ref))</Paragraph>
    <Paragraph position="4"> concept. This is illustrated in the lexical entry for &amp;quot;book&amp;quot; in figure 1.</Paragraph>
    <Paragraph position="5"> Nouns form the bulk of any lexicon and often have direct mappings into the ontology. Therefore, this tool facilitates acquisition significantly by producing many entries that are nearly complete. In contrast, the verbal entries it produces are only partially complete since Word_Net doesn't provide detailed information on subcategorizations and selectional restrictions. Two examples will be given to illustrate the problems that arise in the matching process. The first one is what one would think as a trivial case to match, namely a concept for a simple concrete object, a chair. The other illustrates problems with different ontological decompositions, specifically two different views of singing.</Paragraph>
    <Section position="1" start_page="95" end_page="96" type="sub_section">
      <SectionTitle>
2.1 Direct mapping for &amp;quot;chair&amp;quot;
</SectionTitle>
      <Paragraph position="0"> The/~K hierarchy for the concept CHAIR is shown in figure 2. WordNet has four synsets or senses for &amp;quot;chair&amp;quot;, so each of these are potential candidates for a direct mapping: sl. chair: a seat for one person, with a support for the back s2. professorship, chair: the position of professor s3. president, chairman, chairwoman, chair, chairperson: the officer who presides at the meetings of an organization s4. electric chair, chair, death chair, hot seat: an instrument of death by electrocution that resembles a chair Since synsets 2 and 3 cover the human agent sense of chair, they won't match well with the pK concept. But senses I and 4 will produce similar matches since  A problem that complicates selecting the appropriate sense is that /zK classifies FURNITURE nilder the generic INTERIOR-BUILDING-PARTS whereas WordNet uses the more specific FURNISHINGS.</Paragraph>
    </Section>
    <Section position="2" start_page="96" end_page="96" type="sub_section">
      <SectionTitle>
2.2 Problematic mapping with &amp;quot;sing&amp;quot;
</SectionTitle>
      <Paragraph position="0"> The verb &amp;quot;sing ~ illustrates what could go wrong when trying to match from WordNet to/zK. There are two main reasons for this problem: The WordNet verb hierarchy is much shallower than /~K's event hierarchy; and, the concept of singing has been represented differently. Here is the pK hierarchy for SING: sing: to produce musical sounds with the voice =*human-voice: the sound made through the mouth by human beings =*emit-sound: to create wave-like disturbances in the air</Paragraph>
      <Paragraph position="2"> :=~wave-energy-event: events in which light, sound, etc. waves are transmitted or emitted =#physical-event: events involving physical force =*event: any activity, action, happening, or situation =~alh refers to any concept The salient aspect is singing as emitting waveform energy. In contrast, the WordNet hierarchy of the closest synset for &amp;quot;sing&amp;quot; emphasizes the commttuicative aspects of singing: s2: sing: produce musical tones with the voice =~talk, speak, utter, mouth, verbalize: express in speech =~cornmunicate, ..., transmit feelings: n/a =~interact, ..., act towards others: act together with others =~act, move, take measures, ...: carry out an action The other senses cover miscellaneous meanings of &amp;quot;sing&amp;quot;: sl. sing, deliver by singing: n/a s3. whistle, sing: let off steam; as of tea kettles st. tattle, talk, blab .... : divulge information or secrets; spill the beans Consequently, the hierarchy match will not produce any alignment; and, the similarity match will not be effective since the synset frequency counts are indirectly based on the WordNet hierarchy. But the text match will still be applicable. Plus, since the children &amp; sibling matches are localized, a plausible match can still be generated.</Paragraph>
    </Section>
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