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<Paper uid="C94-2148">
  <Title>UNIVERSAL GUIDES AND FINITENESS AND SYMMETRY OF GRAMMAR PROCESSING ALGORITHMS</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
ABSTRACT
</SectionTitle>
    <Paragraph position="0"> This paper presents a novel technique called &amp;quot;universal guides&amp;quot; which explores inherent properties of logic grammars (changing variable binding status) in order to characterize tbrmal criteria for termination in a derivation process. The notion of universal guides also offers a new framework in which both parsing and generation can be viewed merely as two different instances of the same generic process: guide consumption. This technique generalizes and exemplifies a new and original use of an existing concept of &amp;quot;proper guides&amp;quot; recently proposed in literature for controlling top-down left-to-right (TDLR) execution in logic progrmns. We show that universal guides are independent of a particular grammar evaluation strategy. Also, unlike proper guides they can be specified in the same mmmer for any given algorithm without knowing in advance whether the algorithm is a parsing or a generation algorithm. Their introduction into a grammar prevents as well the occurrence of certain grammar rules an infinite number of times dnring a derivation process.</Paragraph>
  </Section>
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