<?xml version="1.0" standalone="yes"?>
<Paper uid="C94-1024">
  <Title>Disambiguation of Super Pint, of Speech (or Supertags) Ahnost Parsing</Title>
  <Section position="4" start_page="158" end_page="159" type="concl">
    <SectionTitle>
6 Conclusion
</SectionTitle>
    <Paragraph position="0"> Lexica\[ized grammars :i,ssociate with each word richer sgructllre~; (trees ill case ()\[' l'l'A(',s and c~tegories hi case o1' (Joml)hl~tI, ory Ca, l, egoriaJ (',I'\[LI\]t--Ill;ll'S ((\](~(~S.)) OVeI' which tile wor(I specilles synt:t(:gic :lid S(qll;i.lltiC collstrathlts. Ilence every word is asso('ia.ted with ~t uluch la.rger set of lllOl'e COlll\[)\]ex stl'll('tlll'es \[,hail ill the ca,se where the words :.re associated with sta,nda.rd i)a.rts olZsl)eech, llowever, these more complex descriptions alk)w more comple-~ coustraints to be imposed a.nd w,'ified locally on the coutexts in which these words a?pea.r. This fea.ture of lexicalized grammars can be taken a,dvantage of, to further reduce the (lisalnl)iguatioii task of the I)arser, as slmwll in SUlmri.ag disa.ml)igua.i.ion.</Paragraph>
    <Paragraph position="1"> Ileu(:e sui)el'Da,g ~ (lisai, nll)igua(,ioli (;a,l/ Im use(I :t~'; a. g;enera.I i)re-i)a.rsing (:olnl)oneut o\[' lexicalized ~rl'all) Illal' pa i'sels.</Paragraph>
    <Paragraph position="2"> The d(,gree of distiuct, ion l)etwe(m SUlml'(.a.g disaml)igua.tion a.n(I i/arsing va.ries, depen(ling on the. lexicalized g;ranima.r be(us (:onsi(M'ed. l,'or both I/I'A(', an(I C'CG, supertag disaml)igui~tion serves as a, preq)arser filter i;tutt effectively we.eds Oil( iila, l)l)rol)ria, te eIelIl(':llta, ry stl'il('tures (tre.es or categories) givenl the c(mtext of the sentence. It also in(liea.tes the dopenden('ies alnoi~g the elementary stru('tlu'es but not tim spe('ific el)era.ties to lie used l,o coral)(he the strllctul/es or tim it(Idress a.t which the el)era.ties is to be l)erformed &amp;quot;a.ll ahliost parse&amp;quot;, l if c'ases where 1,1l(; SUl)ertag sequelice \[Tir the ~iW.~li hil)ut strilig c:l, llilot lie  combined to form a complete structure, the &amp;quot;atmost parse&amp;quot; may mdee(i be the best one can do. In case of LTAG, even though no exl)licit substitutions or adjunctions are shown, the dependencies among LTAG trees uniquely identify the combining operation between the trees and the node at which the operation (:an be performed is almost always unique s. Thus supertag disambiguation is almost parsing lbr UI'-AGs. In contrast, the dependencies among the CCG categories do not result in directly identifying the combining operations between the categories since two categories can often be corn I)ined in more than one way. Hence for CCG fiu'ther processing needs to be performed to obtain the complete parse of the sentence, although without any supertag ambiguities.</Paragraph>
    <Paragraph position="3"> The supertag disaml)iguation, dependency model in particular, is even closer to p~wsing in dependency grammar formalism, l)ependency parsers establish relationships among words, unlike the phrase-structure parsers which construct a phrase-structure tree spanning the words of the input. Since LTAGs are lexicalized and each elementary tree is associated will, a.t least one lexical item, the supertag disaml)iguation for EPAG can therefore be viewed as establishing the relationship a among words as dependency parsers do. Then the elementary stru(&gt; tures that the related words anchor are combined to reconstruct the phrase-structure tree similar to the result of phrase-structure parsers. Th,s the interplay of both dependency ,~nd phrase-structure grammars can be seen in U\['AGs. Rambow and Joshi (R, ambow and Joshi, 1993) discuss in greater detail the use of LTAC, in reh~ting dei)endency analyses to phrase-structure analyses and I)rOl)OSe a dei)endency-I)ased l)arser for a, phrase-structure based grammar.</Paragraph>
    <Paragraph position="4"> In summary, we have presented a new technique that performs the disambiguation of supertags using local intbrmation such as lexi('al preference and local lexical dependencies. This technique, like part-of-speech disambigua.tlon, ro.duces the disambiguation task that needs to be Sin some cases, the dependency information between an auxiliary and an elementary tree may be insufficient to uniquely identify the address of adjunction, if the auxiliary tree can adjoin to more than one node in the elementary tree, since the specific attachments are not shown.</Paragraph>
    <Paragraph position="5"> 6The relational labels between two words it, L'I'AG is associated with the address of the operation between the trees that the words anchor.</Paragraph>
    <Paragraph position="6"> done 1)y the parser. After the disa.nd)iguation, we have effectively comi)leted the parse of the sentence ~md the parser needs %nly' to coml)lete the ~djunction and substitutions. This method can also serve to parse Selltetlce \['ra~lfleuts ill cases where the supertag sequence after the disambiguation may not contbine to form a single structure. We have implemented this technique of disambiguation using the n-gram models using the prol)ability data collected from LTAG I)arsed corpus. The similarity between lilAC and l)ependency grammars is exploited in the (lependency mo(M of supertag disambigm~tion. The per\['ormance results of these models have been presented.</Paragraph>
  </Section>
class="xml-element"></Paper>