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<Paper uid="W05-1623">
  <Title>Reversibility and Re-usability of Resources in NLG and Natural Language Dialog Systems</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Reversibility is a key factor in building e-cient and maintainable NLG and natural language dialog systems (NLDSs). But previous formal descriptions of reversibility are still lacking in coverage and applicability to existing systems. In this paper, we extend former approaches to this matter by formally deflning reversibility in NLDSs and developing a proper classiflcation of such systems in terms of reversibility. After that, existing NLG and generic dialog systems are used as examples for the feasibility and applicability of our classiflcation.</Paragraph>
    <Paragraph position="1"> In our point of view, it is useless to consider reversibility for an NLG system alone, because parsing and dialog management are equally important for developing an NLDS. Hence, our classiflcation applies to complete dialog systems and not only NLG systems.</Paragraph>
  </Section>
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