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<Paper uid="P90-1015">
  <Title>LICENSING AND TREE ADJOINING GRAMMAR IN GOVERNMENT BINDING PARSING</Title>
  <Section position="8" start_page="116" end_page="116" type="evalu">
    <SectionTitle>
5 Problems and Future Work
</SectionTitle>
    <Paragraph position="0"> Boris knew that Tom ate lunch will not be parsed even though there exist well-formed sets of elementary trees which can derive them. The problem results from the fact that the left to right processing strategy we have adopted is a bit too strict. The complementizer that will be attached as object of know, but Tom is not then licensed by any node on the right frontier. Ultimately, this DP is licensed by the tns/agr morpheme in the lower clause whose IP projection is licensed through functional selection by C. Similarly, the parser would have great difficulty handling head final languages. Again, these problems might be solved using extra-grammatical devices, such as the attention shifting of \[Marcus, 1980\] or some template matching mechanism, but this would entail a process of &amp;quot;compiling out&amp;quot; of the grammar that we have been trying to avoid.</Paragraph>
    <Paragraph position="1"> Finally, phonologically empty heads and head movement cause great difficulties for this mechanism. Heads play a crucial role in this &amp;quot;project and attach&amp;quot; scheme. Therefore, we must find a way of determining when and where heads occur when they are either dislocated or not present in the input string at all, perhaps in a similar manner to the mechanism for movement of maximal projections I have proposed above.</Paragraph>
    <Paragraph position="2"> The parsing model which I have presented here is still rather preliminary. There are a number of areas which will require further development before this can be considered complete.</Paragraph>
    <Paragraph position="3"> I have assumed that the process of projection is entirely determined from lexieal lookup. It is clear, though, that lexical ambiguity abounds and that the assignment of gives and needs to the projections of input tokens is not determinate. An example of such indeterminacy has to do with the assignment to argument maximal projections of theta needs as a result of the them criterion. DPs need not always function as arguments, as I have been assuming.</Paragraph>
    <Paragraph position="4"> This problem might be solved by allowing for the statement of disjunctive constraints or a limited form of parallelism. If the duration of such parallelism could be tightly</Paragraph>
  </Section>
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