Investigating regular sense extensions based on intersective Levin classes

Investigating regular sense extensions based on intersective Levin classes Hoa Trang Dang, Karin Kipper, Martha Palmer, Joseph Rosenzweig Department of Computer and Information Sciences and the Institute for Research in Cognitive Science University of Pennsylvania 400A, 3401 Walnut Street/6228 Philadelphia, PA 19104, USA htd/kipper/mt)almer/josephr@cis.upenn.edu Abstract In this paper we specifically address questions of polysemy with respect to verbs, and how regular extensions of meaning can be achieved through the adjunction of particular syntactic phrases. We see verb classes as the key to making gen- eralizations about regular extensions of mean- ing. Current approaches to English classifica- tion, Levin classes and WordNet, have limita- tions in their applicability that impede their utility as general classification schemes. We present a refinement of Levin classes, intersec- tive sets, which are a more fine-grained clas- sification and have more coherent sets of syn- tactic frames and associated semantic compo- nents. Wc have preliminary indications that the membership of our intersective sets will be more compatible with WordNct than the orig- inal Levin classes. We also have begun to ex- amine related classes in Portuguese, and find that these verbs demonstrate similarly coherent syntactic and semantic properties. 1 Introduction The difficulty of achieving adequate hand- crafted semantic representations has limited the field of natural language processing to applica- tions that can be contained within well-defined subdomains. The only escape from this lim- itation will be through the use of automated or semi-automated methods of lexical acquisi- tion. However, the field has yet to develop a clear consensus on guidelines for a computa- tional lexicon that could provide a springboard for such methods, although attempts are being made (Pustejovsky, 1991), (Copestake and San- filippo, 1993), (Lowe et al., 1997), (Dorr, 1997). The authors would like to acknowledge the sup- port of DARPA graat N66001-94C-6043, ARO grant DAAH04-94G-0426, and CAPES grant 0914/95-2. One of the most controversial areas has to do with polysemy. What constitutes a clear sepa- ration into senses for any one verb, and how can these senses be computationally characterized and distinguished? The answer to this question is the key to breaking the bottleneck of semantic representation that is currently the single great- est limitation on the general application of nat- ural language processing techniques. In this paper we specifically address questions of polyscmy with respect to verbs, and how regular extensions of meaning can be achieved through the adjunction of particular syntactic phrases. We base these regular extensions on a fine-grained variation on Levin classes, inter- sective Levin classes, as a source of semantic components associated with specific adjuncts. Wc also examine similar classes in Portuguese, and the predictive powers of alternations in this language with respect to the same semantic components. The difficulty of determining a suitable lcxical representation becomes multi- plied when more than one language is involved and attempts are made to map between them. Preliminary investigations have indicated that a straightforward translation of Levin classes into other languages is not feasible (Jones et al., 1994), (Nomura et al., 1994), …

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