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<Paper uid="C96-1025">
  <Title>Processing Metonymy: a Domain-Model Heuristic Graph Traversal Approach*</Title>
  <Section position="3" start_page="0" end_page="137" type="intro">
    <SectionTitle>
2 Metonymy and type coercion
</SectionTitle>
    <Paragraph position="0"> A (:lassical exainple of metonynly (Pustejovsky, 1.991, It. 428ff) is  (1) John began a novel.</Paragraph>
    <Paragraph position="1">  where predicate 'began' expects an event as its second argument, so that some way must be found to relate the object 'novel' to an event such as 'to read a novel' or 'to write a novel'. In our domain (coronary diseases), one often finds expressions such as  (2) une angioplastie du segment II (an angioplasty of segment II) (3) une angioplastie d'une artbre coronaire (an angioplasty of a coronary artery) (4) l'angioplastie de Monsieur X (the angioplasty of Mr X) (5) une angioplastie de la st6nose (an angioplasty  of the stenosis) where 'angioplasty' is an action performed on a segment of an artery to enlarge its diameter, while 'stenosis' is the state of an artery which has a reduced diameter. These four phrases involve the object (or &amp;quot;theme&amp;quot;) of action 'angioplasty', i.e., what the angioplasty operates upon. If one considers that this theme must be a physical object, then examples (2)-(4) conform to the selectional restrictions of 'angioplasty', while (5) violates them. The mechanism of type coercion (Pustejovsky, 1991) consists in converting a word type into another so that semantic composition can work properly. (5) is then handled as a metonymy, where the stenosis and the stenosed object enter a state/thing alternation: 'stenosis' is turned into an 'object'.</Paragraph>
    <Paragraph position="2"> However, it appears that this phenomenon is dependent on the underlying types (or &amp;quot;sorts&amp;quot;) under consideration. For instance in our ontology, 'segment', 'artery', 'stenosis' and 'human' have four different types, and are not comparable by the IS-A relation, e.g. nothing can be both a segment and an artery} This is a voluntary, methodological choice (Bouaud et al., 1995), motivated by the fact that these objects give rise to different inferences and must not be confused by the reasoning component. Additionally, in the target normalised conceptual representation, what constitutes the specific theme (in our conceptual model, the purported_oh j) of action 'angioplasty' must be precisely defined. In the context of our application, 'angioplasty' acts on an artery_segment, a physical object corresponding to a part of an artery, which happens not to be comparable to any of the four preceding themes of 'angioplasty'. 2 Therefore, all four examples (2)-(5) must be considered as metonymies.</Paragraph>
    <Paragraph position="3"> 1Segment, in our ontology, corresponds to a portion of space, not of matter.</Paragraph>
    <Paragraph position="4"> 2Notice, though, that these types are strongly linked (by relations other than IS-A) through the knowledge base models. The semantic analyser precisely recovers these links thanks to the mechanism presented in this paper.</Paragraph>
    <Paragraph position="5"> To handle metonymy, Fass (1988) proposes a method based on a list of alternations implemented as specific metonymy rules: Part_for_Whole, Container-for_Contents, etc. Sowa (1992) considers metonymies around the term &amp;quot;Prix Goncourt&amp;quot;, originally introduced by Kayser (1988): this term undergoes different meaning shifts in each of seven example sentences, ranging from the author who won the prize to the amount of money received. Sowa discusses how background knowledge could help to process these metonymies, based on a knowledge description of what &amp;quot;Prix Goncourt&amp;quot; involves.</Paragraph>
    <Paragraph position="6"> In our system, the target conceptual representation is defined by a domain model expressed with CGs. This same model constitutes the resource which enables the analyser to handle metonymies. We explain below how results similar to Pustejovsky's type coercion may be obtained with a method based on this domain model instead of a qualia structure.</Paragraph>
  </Section>
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