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<Paper uid="W97-1514">
  <Title>An Object-Oriented Linguistic Engineering Environment using LFG (Lexical Functionnal Grammar) and CG (Conceptual Graphs)</Title>
  <Section position="3" start_page="0" end_page="99" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
1.1 Generalities
</SectionTitle>
      <Paragraph position="0"> Natural language processing is nowadays strongly related to Cognitive Science, since linguistics, psychology and computer science have to collaborate to produce systems that are useful for man-machine communication. This collaboration has allowed formalisms that are both theoretically well-founded and implementable to emerge. In this paradigm, we have conceived and developed a linguistic software engineering environment, whose goal is to set up reusable and evolutive toolkits for natural language processing (including collecting linguistic data, analysing them and producing useful data for computer processes). Based on a large number of graphical, very intuitive, interfaces, this environment has two main goals: * to provide tools usable by users outside the field of Computer Science (e.g., computational linguists) for them to be able to easily collect data and test their linguistic hypotheses * to allow computer scientists to exploit these data in computer programs Remark: in the text, some figures describe the structure of our tools; we have used Booch's conventions (Booch, 1994) about object oriented analysis and conception. They are summarized here:</Paragraph>
    </Section>
    <Section position="2" start_page="0" end_page="99" type="sub_section">
      <SectionTitle>
1.2 Extensions to LFG formalism
</SectionTitle>
      <Paragraph position="0"> Four types of equations are defined in classical LFG (Bresnan and Kaplan, 1981):  1. unifying structures (symholised by &amp;quot;-&amp;quot;), 2. constrained unification of structures, only true if a feature is present in both structures, but may not be added (symbol &amp;quot;=c&amp;quot;), 3. obligatory presence of a feature (symbol &amp;quot;~&amp;quot;), 4. obligatory absence of a feature (symbol tilde).  We have defined three non-standard types of equa- null tions used in our parser: 1. obligatory difference between two values (symbol &amp;quot;#&amp;quot;), 2. disjunction of obligatory differences (a sequence of obligatory differences separated by the symbol &amp;quot;1&amp;quot;) (this can also be viewed as the negation of a conjonction of obligatory presences) 3. prioritary union, copy into a F-Structure the attributes of the other that are not present in the first one, nor inconsistent with it.</Paragraph>
      <Paragraph position="1"> Among other existing systems (e.g., A. An null drew's system , Charon, The &amp;quot;Konstanz LFG Workbench&amp;quot; and Xerox &amp;quot;LFG Workbench&amp;quot;; see http://clwww.essex.ac.uk/LFG for more details on these systems), only the last one is a complete environment for editing grammars and lexicons. Our system adds to this feature an open architecture and many interfaces that make it very easy to use.</Paragraph>
    </Section>
  </Section>
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