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<Paper uid="N03-3008">
  <Title>Investigations on Event Evolution in TDT</Title>
  <Section position="7" start_page="0" end_page="0" type="concl">
    <SectionTitle>
6 Conclusion
</SectionTitle>
    <Paragraph position="0"> We have discussed three problems relating to TDT and mainly its event evolution. The novel topic definition allows the topic to evolve into several directions and ultimately to distinguish new topics. A semantic class-based event vector enables harnessing of domain specific ontologies, such as the time-axis and the geographic distances. Finally, we presented a TDT system with dynamic hierarchies that would cut down the excessive computation required in the TDT process.</Paragraph>
    <Paragraph position="1"> Our previous results were done with a Finnish online news corpus smaller than the TDT corpora (Makkonen et al., 2002). The use of semantic classes proved to be beneficial. We have also built a temporal expression scheme and a geographical ontology for TDT purposes (Makkonen et al., 2003). In this paper, all our discussions were preliminary and should be regarded as such. In the future we will work to motivate these mostly intuitive theories with empirical results.</Paragraph>
  </Section>
class="xml-element"></Paper>