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<Paper uid="W98-0501">
  <Title>Towards an implementable dependency grammar</Title>
  <Section position="4" start_page="2" end_page="3" type="intro">
    <SectionTitle>
2 Constituency vs. dependency
</SectionTitle>
    <Paragraph position="0"> A central idea in American structuralism was to develop rigorous mechanical procedures, i.e. &amp;quot;discovery procedures&amp;quot;, which were assumed to decrease the grammarians' own, subjective assessment in the induction of the grammars.</Paragraph>
    <Paragraph position="1"> This practice was culminated in Harris (1960, p. 5), who claimed that &amp;quot;the main research of descriptive linguistics, and the only relation which will be accepted as relevant in the present survey, is the distribution or arrangement within the flow of speech of some parts or features relative to others.&amp;quot; The crucial descriptive problem for a distributional grammar (i.e. phrase-structure grammar) is the existence of non-contiguous elements. The descriptive praxis of some earlier IC theoricians allows discontiguous constituents.</Paragraph>
    <Paragraph position="2"> For example, already Wells (1947) discussed the problem at length and defined a restriction for discontiguous constituents 6. Wells' restriction implies that a discontiguous sequence can be a constituent only if it appears as a contiguous sequence in another context. This means that Wells' characterisation of a constituent defines an element which is broadly equivalent to the notion of bunch in Tesni~re's (1959} theory. Consequently, these two types of grammars are capable of describing the equivalent syntactic phenomena and share the assumption that a syntactic structure is compatible with its semantic interpretation. However, the extended constituent grammar thus no longer provides a rigorous distributional basis for a description, and its formal properties are unknown.</Paragraph>
    <Paragraph position="3"> We can conclude our argument by stating that the reason to reject constitutional grammars is that the formal properties for descrip6Wells (1947): &amp;quot;A discontinuous sequence is a constituent il in some environment the corresponding continuous sequence occurs as a constituent in a construction semantically harmonious with the constructions in which the given discontinuous sequence occurs.&amp;quot; Further, Wells notes that &amp;quot;The phrase semantically harmonious is left undefined, and will merely be elucidated by examples.&amp;quot;  tively adequate constitutional grammars are not known. In the remaining sections, we show that a descriptively adequate dependency model can be constructed so that it is formally explicit and parsable.</Paragraph>
  </Section>
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