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<Paper uid="P98-1093">
  <Title>Information Classification and Navigation Based on 5W1H of the Target Information</Title>
  <Section position="7" start_page="576" end_page="576" type="relat">
    <SectionTitle>
7 Related Work
</SectionTitle>
    <Paragraph position="0"> SOM (Self-Organization Map) is an effective automatic classification method for any data represented by vectors (Kohonen, 1990). However, the meaning of each cluster is difficult to understand intuitively.</Paragraph>
    <Paragraph position="1"> The clusters have no logical meaning because they depend on a keyword set based on the frequency that keywords occur.</Paragraph>
    <Paragraph position="2"> Scatter/Gather is clustering information based on user interaction (Hearst and Pederson, 1995; Hearst et al., 1995). Initial cluster sets are based on key-word frequencies.</Paragraph>
    <Paragraph position="3"> GALOIS/ULYSSES is a lattice-based classification system and the user can browse information on the lattice produced by the existence of keywords (Carpineto and Romano, 1995).</Paragraph>
    <Paragraph position="4"> 5WlH classification and navigation is unique in that it is based on keyword functions, not on the existence of keywords.</Paragraph>
    <Paragraph position="5"> Lifestream manages e-mail by focusing on temporal viewpoints (Freeman and Fertig, 1995). In this sense, this idea is similar to our episodic retrieval though the purpose and target are different.</Paragraph>
    <Paragraph position="6"> Mine et al. and Hyodo and Ikeda reported on the effectiveness of using dependency relations between keywords for retrieval (Mine et al., 1997; Hyodo and Ikeda, 1994).</Paragraph>
    <Paragraph position="7"> As the 5WlH index is more informative than simple word dependency, it is possible to create more functions. More informative indexing such as semantic indexing and conceptual indexing can theoretically provide more sophisticated classification. However, this indexing is not always successful for practical use because of semantic analysis difficulties. Consequently 5WlH is the most appropriate indexing method from the practical viewpoint.</Paragraph>
  </Section>
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