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<Paper uid="P90-1038">
  <Title>BOTTOM-UP PARSING EXTENDING CONTEXT-FREENESS IN A PROCESS GRAMMAR PROCESSOR</Title>
  <Section position="8" start_page="304" end_page="305" type="relat">
    <SectionTitle>
6. RELATED WORKS
</SectionTitle>
    <Paragraph position="0"> Some comparisons can be made with related works on three main levels: the data structure PGS; the Process Grammar; the PG Processor.</Paragraph>
    <Paragraph position="1"> ThePGS can be compared with the chart (Kaplan, 1973; Kay, 1982). The PGS embodies much of the information the chart has. As a matter of fact, our PGS can be seen as a denotational variant of the chart, and it is managed in a different way by the PG Processor since in the PGS we mainly use classical relations between the nodes of the parse-trees: the dominance relation between a parent and a son node, encoded in the non-terminal nodes; the leftadjacency relation between subtrees, encoded in the terminal nodes. Note that if we add the fight-adjacency relation to the PGS we obtain a structure fully comparable to the chart.</Paragraph>
    <Paragraph position="2"> The Process Grammar can embody many kinds of information. Its structure comes from the general structure stated for the APSG, being very close to the ATN Grammars structure. On the other hand, our approach proposes that grammar rules contain directives relative to the control of the parsing process. This is a feature not in line with the current trend of keeping separate control and linguistic restrictions expressed in a declarative way, and it can be  found in parsing systems making use of grammars based on situation-action rules 0Vinograd, 1983); furthermore, our way of managing grammar rules, i.e., operations on the states, activation and scheduling mechanisms, is very similar to that realized in Marcus (1980).</Paragraph>
  </Section>
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