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<Paper uid="W99-0632">
  <Title>Using Subcategorization to Resolve Verb Class Ambiguity</Title>
  <Section position="3" start_page="0" end_page="266" type="intro">
    <SectionTitle>
2 Motivation
</SectionTitle>
    <Paragraph position="0"> Levin provides an index of 3,024 verbs for which she lists the semantic classes and diathesis alternations. The mapping between verbs and classes is not one-to-one. Of the 3,024 verbs which she covers, 784 are listed as having more than one class.</Paragraph>
    <Paragraph position="1"> Even though Levin's monosemous verbs outnumber her polysemous verbs by a factor of nearly four to one, the total frequency of the former (4,252,715) is comparable to the total frequency of the latter (3,986,014). This means that close to half of the cases processed by a hypothetical semantic tagger would manifest some degree of ambiguity. The frequencies are detailed in table 1 and were compiled from a lemmatized version of the British National Corpus (BNC), a widely distributed 100 million word collection of samples of written and spoken English (Burnard, 1995).</Paragraph>
    <Paragraph position="2">  Furthermore, as shown in figure 1, the number of alternations licensed by a given verb increases with the number of classes it inhabits. Consider for example verbs participating in one alternation only: of these, 90.4% have one semantic class, 8.6% have two classes, 0.7% have three classes and 0.3% have four classes. In contrast, of the verbs licensing six different alternations, 14% have one class, 17% have two classes, 12.4% have three classes, 53.6% have four classes, 2% have six classes and 1% has seven classes.</Paragraph>
    <Paragraph position="3"> Palmer (1999) and Dang et al. (1998) argue that the use of syntactic frames and verb classes can simplify the definition of different verb senses. Beyond this, we claim that information about the argument structure of a polysemous verb can often help disambiguating it.</Paragraph>
    <Paragraph position="4"> Consider for instance the verb serve which is a member of four classes: GIVE, FIT, MASQUERADE and FULFILLING. Each of these classes can in turn license four distinct syntactic frames. As shown in the examples I below, in (4a) serve appears ditransitively and belongs to the semantic class of GIVE verbs, in (4b) it occurs transitively and is a member of the class of FIT verbs, in (4c) it takes the predicative complement as minister of the interior and is a member of MASQUERADE verbs. Finally, in sentence (4d) serve is a FULFILLING verb and takes two complements, a noun phrase (an apprenticeship) and a prepositional phrase headed by to. In the case of verbs like serve we can guess their semantic class solely on the basis of the frame with which they appear.</Paragraph>
    <Paragraph position="5">  (4) a. I'm desperately trying to find a venue for the reception which can serve our guests an authentic Italian meal.</Paragraph>
    <Paragraph position="6"> b. The airline serves 164 destinations in over 75 countries.</Paragraph>
    <Paragraph position="7"> c. Jean-Antoine Chaptal was a brilliant chemist and technocrat who served  Napoleon as minister of the interior from 1800 to 1805.</Paragraph>
    <Paragraph position="8"> d. Before her brief exposure to pop stardom, she served an apprenticeship to a still-life photographer.</Paragraph>
    <Paragraph position="9"> But sometimes we do not have the syntactic information that would provide cues for semantic disarnbiguation. Consider sentence (5a). The verb write is a member of three Levin classes, two of which (MESSAGE TRANSFER, PERFORMANCE) take the ditransitive flame NP-V-NP-NP. In this case we have the choice between the &amp;quot;message transfer&amp;quot; reading (cf. (5a)) and the &amp;quot;performance&amp;quot; reading (cf. (Sb)). This is an instance of the common problem of inferring the value of a hidden variable (in this case the &amp;quot;true class&amp;quot; of a particular instance of write). The same situation arises with the verb phone which is listed as a GET verb and an INSTRU-</Paragraph>
  </Section>
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