<?xml version="1.0" standalone="yes"?>
<Paper uid="E83-1020">
  <Title>A FLEXIBLE NATURAL LANGUAGE PARSER BASED ON A TWO-LEVEL REPRESENTATION OF SYNTAX</Title>
  <Section position="7" start_page="120" end_page="120" type="concl">
    <SectionTitle>
CONCLUDING REMARKS
</SectionTitle>
    <Paragraph position="0"> The paper describes a parser for a large sub set of Italian. The novel control structure in volves the use of natural changes which restructure the tree representing the status of the analysis without the intervention of the backup mechanism.</Paragraph>
    <Paragraph position="1"> This allows the system to operate in a pseudo-dete~ ministic way, in that the use of backup is limited to sentences which could make people garden path.</Paragraph>
    <Paragraph position="2"> Another major feature of the parser is its a bility to cope with some kinds of ill-formedness of the input sentences. This is obtained by a decomp~ sition of the syntactic knowledge into two levels: the first level contains structure building rules, whereas the second level contains rules of agree ment and rules related with the ordering of constit uents. This structuring of the syntactic knowledge allows the parser to be data driven: the scanning of a new input word produces its insertion into the analysis tree; this may be seen as an hypothesis of interpretation, which can be accepted or rejected later on the basis of other independent knowledge sources. This allows the system to avoid the use of classical rewriting rules or transition networks which represent in an integrated way all syntactic constraints.</Paragraph>
    <Paragraph position="3"> As stated in the introduction, the authors are developing a N.L. interface to a relational data base. The lexical analyzer and the access proce dures to the network representing the semantic con straints are running, the construction rules and the natural changes are being debugged, whereas the ordering rules are under development. The transla tion into the actual data base query is running.</Paragraph>
    <Paragraph position="4"> The system is written in FRANZ LISP and runs on a VAX 11/780 under the UNIX operating system.</Paragraph>
  </Section>
class="xml-element"></Paper>