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<Paper uid="W90-0115">
  <Title>The Basic Block Model of Extended Explanations</Title>
  <Section position="14" start_page="116" end_page="117" type="concl">
    <SectionTitle>
CONCLUSIONS
</SectionTitle>
    <Paragraph position="0"> This paper has identified several characteristics of naturally-occurring explanations that cannot be accounted for by recursive text organization strategies.</Paragraph>
    <Paragraph position="1"> While recursive methods such as RST and schemas are SSee \[Mooney, et al. 1989\] for a more complete discussion.</Paragraph>
    <Paragraph position="2">  adequate for local organization of text, they are insufficient for the determination of high-level structure, providing neither criteria which describe what constitutes an acceptable framework for a discourse nor any clues as to how this framework should be constructed. We have presented a computational strategy for generating the high-level structure for extended explanations that addresses both issues. Our strategy is based on the basic block, a discourse unit consisting of an organizational focus and text structured about that focus. We contend that basic block structure cannot be adequately generated by recursive structur{ng methods, but must be identified by bottom-up strategies driven by the information to be conveyed. Support for our contentions is provided by repetition, a device frequently used in extended explanations for a variety of purposes.</Paragraph>
    <Paragraph position="3"> Our anMysis of high-level structure suggests a strategy for generating extended explanations which we are currently implementing as part of a larger system designed to generate extended explanations in an interactive environment. The system is intended as a testbed for identifying viable organizational strategies and recovery techniques due to user interruptions within the basic block paradigm. We believe that our analysis of basic block structure provides criteria necessary for bridging the gap between the generation of short explanations and the successful generation of extended explanations by explicating how the framework of an extended explanation can be constructed and how repetition can be cohesively incorporated into it.</Paragraph>
  </Section>
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