Varying Cardinality in Metonymic Extensions to Nouns

Varying Cardinality in Metonymic Extensions to Nouns Helmut Horacek Universität des Saarlandes F.R. 6.2 Informatik Postfach 151150 D-66041 Saarbrücken, Germany email: horacek@cs.uni-sb.de Abstract Meaning shifting phenomena such as metonymy have recently attracted increasing interest of researchers. Though these phenomena have been addressed by plenty of computational methods, the impacts of cardinalities of metonymically related items have been widely ignored in all of them. Motivated by this lack of analysis, we have developed a method for representing expect- ations and knowledge about the cardinalities of metonymically related entities and for exploiting this information to build logical forms express- ing metonymic relations, the entities related, and their cardinalities. The representation of lexically motivated knowledge is realized as an enhan- cement to Pustejovsky's Generative Lexicon, and the process of building logical forms takes into account overwriting of default information and mismatch of cardinality requirements. Our method enables a precise attachment of sentence complements, and it supports reference reso- lution in the context of metonymic expressions. 1 Introduction Meaning shifting phenomena such as metonymy have recently attracted increasing interest. Com- putational approaches to these phenomena aim at inferring implicitly represented relations, predict- ing meaning shifts of nouns or verbs, expressing restrictions on these meaning shifts in depen- dency of context- or language-specific factors, and facilitating reference resolution. Measures to achieve these issues include representation of default knowledge and various sorts of inference methods and constructive procedures. However, the entities in the texts examined almost always appear in singular form so that issues of cardina- lity of metonymically related items have been widely ignored by the approaches made so far. Motivated by this lack of analysis, we have examined metonymic expressions by varying cardinalities of the items appearing explicitly or implicitly, to analyze effects of these alternations. The results have inspired us to build increasingly explicit versions of logical forms, and to formul- ate conditions on pronominal accessibility. The insights gained improve analysis methods for relating contextual specifications to the appropri- ate entity, and for supporting reference reso- lution to entities related implicitly. This paper is organized as follows. We review computational approaches to metonymy. Then we illustrate the phenomena investigated. We elaborate suitable techniques to deal with these phenomena, that is, an enhancement to entries in the Generative Lexicon, and a procedure for building a logical form. Finally, we discuss im- pacts of our analysis on pronominal resolution. 2 Approaches to Metonymy Metonymy is a natural language phenomenon that contributes to expressing information in an effective and economic way. It involves what has been termed 'transfers of meaning' by (Nunberg 1995), i.e., the meaning of some constituent does not correspond to what can be expected accord- ing to the syntactic and semantic environment – the speaker is "using one entity to refer to another that is related to it" (Lakoff and Johnson 1980). For example, in the utterance "The ham sandwich is waiting for his check", it is not literally the ham sandwich, which wants to pay, but the person who ordered it. Computational …

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