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<Paper uid="C00-1003">
  <Title>Selectional Restrictions in HPSG</Title>
  <Section position="7" start_page="18" end_page="19" type="concl">
    <SectionTitle>
4 Conclusions
</SectionTitle>
    <Paragraph position="0"> We have presented two met;hods to incorporate selectional restrictions ill IlPSG: (i) expressing selectional restrictions as BACKGROUND constraints, and (it) enq)loying subsorts of referentrial indices. The first method has the advantage that it requires no modification of the cmTent IIPSO feature structures. It also lnzdntains Pollard and Sag's distinction bel;ween &amp;quot;literal&amp;quot; mid &amp;quot;non-literal&amp;quot; meaning (expressed t)y CeNT and I~ACKGI/OUN\]) respe, ctively), a distinction whi('h is lflm'red in the second approach (e.g. nothing in (18) shows th~lt requiring the obje('t to denote an edil)le entity is part of the non-literal meaning; of. (10)). Unlike the tirst method, however, the second apt)roach re(tuires no additional taft;renting comtionent tbr determining when selecl;ional restrictions h~tve been violated. With sentences that contain several potentially aiillfiguous words or phrases, t;11(,, second apl)roat:h is also more etlicienl;, ~ls it blocks signs that violalx', selectionnl testa'tel;ions during parsing.</Paragraph>
    <Paragraph position="1"> In the tirsl; aplm)ach, these signs remain undetected during parsing, and they may have a multiplicative effect, h;ading to a large nmnber of parses, which then have to l)e checked individually by the taft;renting component. We have timnd the se(:ond at)l)roach t)articularly useful in the develolnnent of practical systems.</Paragraph>
    <Paragraph position="2"> There is a deet)er question here al)out the proper place to maintain the kind of intbrnlalion encoded in selectional restrictions. The applicability of selectional restrictions is always context-dependent; and for any selectional restriction, we can ahnost always find a context where it does not hold. Our second method above effectively admits that we cromer develop a general tmrlIosc solution to the problem of meaning interprel;ation, and that we have to atcept that our systems alwws operate in specific contexts. By committing to a particular context of interpretation, we 'compile into' what was traditionally thought of as literal meaning a  set of contextually-determined constraints, and thus enable these constraints to assist in the HPSG language analysis without requiring an additional reasoning component. We take the view here that this latter approach is very appropriate in the construction of real applications which are, and are likely to be ibr the tbreseeable future, restricted to operating in limited domains.</Paragraph>
  </Section>
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