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<Paper uid="C80-1008">
  <Title>A RULE-BASED APPROACH TO ILL-FORMED INPUT</Title>
  <Section position="5" start_page="49" end_page="49" type="concl">
    <SectionTitle>
5. Conclusion
</SectionTitle>
    <Paragraph position="0"> Our hypothesis is that both absolute and relative ill-formedness should be treated as rule-based. Rules for well-formed input should be employed first. The detailed way in which the rules of well-formed input are violated signal which meta-rule(s) to use to relate the structure of the ill-formed input to a well-formed one. The meta-rules show how well-formed rules should be modified to interpret i\]l-formed input as completely as possible.</Paragraph>
    <Paragraph position="1"> There are at least three ways to proceed in order to strengthen that hypothesis: i) Reformulating the popular technique of explicitly encoding ill-formed patterns of an ATN within the methodology, 2) Developing strategies for additional classes of ill-formedness: a) merged thoughts or run-on sentences. An example is &amp;quot;Give me a list of the supplier's list.&amp;quot; b) wrong word choice. An example is &amp;quot;Computer the standard deviation...&amp;quot; instead of &amp;quot;Compute the standard deviation...&amp;quot; This could not be treated as a spelling error if both &amp;quot;compute&amp;quot; and &amp;quot;computer&amp;quot; were in the lexicon. Hence, it would have to be treated as incorrect word choice.</Paragraph>
    <Paragraph position="2"> c) &amp;quot;expansion&amp;quot; ellipsis. Expansion ellipsis is a kind of fragmentary input no system has processed before. An example would be a response of &amp;quot;On employee name&amp;quot; to a question, &amp;quot;Should the list be printed in alphabetical order?&amp;quot; null d) violation of semantic constraints.</Paragraph>
    <Paragraph position="3"> An ill-formed input such as &amp;quot;Have we ordered supplier 34?&amp;quot; violates semantic constraints, since a supplier is not semething that can be ordered. We plan to develop techniques that will recognize this semantic Violation and hypothesize that &amp;quot;Have we ordered frc~n supplier 34?&amp;quot; was intended.</Paragraph>
    <Paragraph position="4"> 3) Improving ill-formedness handling by parallel processing of lexical, semantic, syntactic, and pragmatic components: a) interaction of semantics and syntax for explaining the cause of misunderstanding when no interpretation is possible, b) pragmatic and semantic overshoot.</Paragraph>
    <Paragraph position="5"> An example of overshoot is asking, &amp;quot;What are the average weights of all rock samples?&amp;quot; when the system has no such weights. This could not be' detected by dictionary lookup if the data base has weights of atcmic elements and has data on rock samples, just not their weights. We intend to develop strategies to detect overshoot and respond appropriately; for the example, an appropriate response is &amp;quot;The system has no weights of rock samples.&amp;quot; We are engaged in a research program involving work on these three problems. All of the rules and meta-rules that we have already developed or are developing will be tested in one of two systems. One is an English front end to data base systems; this research-oriented natural language processor is under development in the Software Research Department of Sperry Univac. The second is a question-answering system (with English input) is being constructed at the University of Delaware.</Paragraph>
    <Paragraph position="6"> We believe that sophisticated understanding and response to ill-formed input is the missing ingredient in making natural language interaction truly natural.</Paragraph>
  </Section>
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