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<Paper uid="C86-1142">
  <Title>The procedure to construct a word predictor in a speech understanding system from a task-specific grammar defined ill a CFG or a DCG</Title>
  <Section position="4" start_page="605" end_page="605" type="concl">
    <SectionTitle>
5. Conclusions
</SectionTitle>
    <Paragraph position="0"> In this paper we have proposed the procedure to convert a grammar defined in a CFG or a DCG into a Prolog program which functions as a word predictor.</Paragraph>
    <Paragraph position="1"> The procedure is give@ for the left-to-right control, but it is not difficult to expand it for the island-driven control.</Paragraph>
    <Paragraph position="2"> To simplify the description, we have given the conversion procedure for a grammar defined in a CFG, but it is easy to expand it for a grammar defined in a DCG, As long as one concernes on a speech understanding system in which syntax and semantics are well defined, one could take an advantage of a DCG in which a nonterminal can have some arguments as parameters, and could use semantic restrictions effectively to interpret an utterance. In developing a speech understanding system of which the task is to access a database, we use semantic markers to describe semantic restrictions between an adjective and a noun, a noun phrase and a postposition (in Japanese), and case slots of a verb and its fillers. In this case a rule can be expressed as follows: C(So) -&gt; \[Po(So, SI)}CI(SI){PI(SI,S2)}C2(S2)...</Paragraph>
    <Paragraph position="3"> {Pn_l(Sn_l,Sn))Cn(Sn), where S~ (i=O,l .... n) is a list of semantic markers, Pi (i=l,2 .... n) is a predicate to denote a constraint among semantic markers. Considering a transition network for this DCG rule, we associate P. with its \] i-th state and let Pi function as a converter of semantic markers. Since Pi would be defined in the form of a table, this converter could work bidirectionally. In addition, stacking a pair&amp;quot; of a syntactic goal variable and a list of semantic markers in the parsing history, we can develop a procedure to transform a grammar described in a DCG into a word predictor.</Paragraph>
  </Section>
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