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<Paper uid="P98-2150">
  <Title>An Estimate of Referent of Noun Phrases in Japanese Sentences</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
YAGATE OJIISAN-WA NEMUTTE-SHIMATTA.
</SectionTitle>
    <Paragraph position="0"> (soon) (old man) (fall asleep) (He (= the old man) soon fell asleep.)</Paragraph>
    <Paragraph position="2"> When dealing with a situation like this, it is necessary for a machine translation system to recognize that the two &amp;quot;OJIISAN (old man)&amp;quot; have the same referent. In this paper, we propose a method that determines the referents of noun phrases by using (1) the referential properties of noun phrases, (2) the modifiers in noun phrases, and (3) the possessors of entities denoted by the noun phrases.</Paragraph>
    <Paragraph position="3"> 1 The possessor of a noun phrase is defined as the entity which is the owner of the entity denoted by the noun phrase. For languages that have articles, like English, we can use articles (&amp;quot;the&amp;quot;, &amp;quot;a&amp;quot;, and so on) to decide whether a noun phrase has an antecedent or not.</Paragraph>
    <Paragraph position="4"> Ill contrast, for languages that have no articles, like Japanese, it is difficult to decide whether a noun phrase has an antecedent. We previously estimated the referential properties of noun phrases that correspond to articles for the translation of Japanese noun phrases into English (Murata and Nagao 1993).</Paragraph>
    <Paragraph position="5"> By using these referential properties, our system determines the referents of noun phrases in Japanese sentences. Noun phrases are classified by referential property into generic noun phrases, definite noun phrases, and indefinite noun phrases. When the referential property of a noun phrase is a definite noun phrase, the noun phrase can refer to the entity denoted by a noun phrase that has already appeared.</Paragraph>
    <Paragraph position="6"> When the referential property of a noun phrase is an indefinite noun phrase or a generic noun phrase, the noun phrase cannot refer to the entity denoted by a noun phrase that has already appeared.</Paragraph>
    <Paragraph position="7"> It is insufficient to determine referents of noun phrases using only the referential property. This is because even if the referential property of a noun phrase is a definite noun phrase, the noun phrase does not refer to the entity denoted by a noun phrase which has a different modifier or possessor. Therefore, we also use the modifiers and possessors of noun phrases in determining referents of noun phrases.</Paragraph>
    <Paragraph position="8"> In connection with our approach, we would like to emphasize the following points: * So far little work has been done on determining the referents of noun phrases in Japanese.</Paragraph>
    <Paragraph position="9"> * Since the Japanese language has no articles, it is difficult to decide whether a noun phrase has an antecedent or not. We use referential properties to solve this problem.</Paragraph>
    <Paragraph position="10"> * We determine the possessors of entities denoted by noun phrases and use them like modifiers in estimating the referents of noun phrases. Since the method uses the sematic relation between an entity and the possessor, which is a language-independent knowledge, it can be used in any other language.</Paragraph>
  </Section>
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