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<Paper uid="C88-2147">
  <Title>Feature Structures Based Tree Adjoining Grammars 1</Title>
  <Section position="5" start_page="718" end_page="718" type="concl">
    <SectionTitle>
4 Conclusions and }~Nl~ure Work
</SectionTitle>
    <Paragraph position="0"> We have shown a method of embedding TAG's in a feature structmm based framewoC/k. This system takes advantage of the extended domain of locality of TAG's and allows lingusitic statements abont cooccurencc of features of dependent iterrLs to be stated within elententary trees. We have shown thst we can make a clearer statement of adjoining constraints in FTAG'a than in TAG's. The specification of local constraints in a 'tAG is by enmneration, which is not satisfactory from the liuguistic point of view. We show that in FTAG, we em~ avoid such specilications, instead the dedarative statements nrade about nodes are sufficient to mmure Ihat only the appropriate flees get adjoined at a node. Furthermore, we also illu.strate how duplication or iuformation can be aw~ided in FTAC's in comparisoJ~ with TA(Us. I~ cau bc shown that aualyses~ that require ex tensions of TA($'s using multi-component adjoining (simultaneous adjunc lion of a set of trees in distinct nodes of an dementary tree) ~ defined in \[\]oshi 1987, Kroeh 1987\], can be easily stated iu FTAG's.</Paragraph>
    <Paragraph position="1"> It is possible to parse an I,&amp;quot;\]?A(I grammar using the Earley-style parsel given by \[Sehabes et aL 1988\]. This l,;arley-style parser can extended in the same way that Sheiber extended the Earley parser lee PA'I3I: II \[Slfieber 1985b\]. The reason this extensi,~lt of the TAll parser to one fl)t I:'FAG is po,~;sible fi)llows from the lact that the treatment of haviJ,g the t and b feature structures fl)r every node in F'I)A(~ is compatible with the I characterization, adopted in the parsing algorithm in \[Schabes et al. :19881, of a node in le.rms of two subs\[rings.</Paragraph>
    <Paragraph position="2"> In \[Vii ayashanker 1987\], we haw~ prop osed a restr toted version (.f FTA G In a manaer similar to GPSG, we place a bound on the information content or' feature structures associated with the nodes of trees used ill the grammar. The resulting system, 1U&amp;quot;TAG, g~nerates the same language as TAG's, and yet retains an increased descriptive and geaeraLive capacity due to the extended domain of locality o{ TAG's.</Paragraph>
    <Paragraph position="3"> Fiually, in this lml)er, we have brMly discussed a calculus to represent FTAG grammars. This cab:alas is an exteation of the llounds-Kasper logic for fi:ature structures, q'he extmltions deM with A abstraction ove~ ~ feature structures and flmetiou application, which is used to ehagacterizd auxiliary trees and the adjunctiml operation. \[Vijayashanker 19871 Lives a detailed description of this calculus and its semantics.</Paragraph>
  </Section>
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