tailieunhanh - Báo cáo khoa học: "Beyond NomBank: A Study of Implicit Arguments for Nominal Predicates"

Despite its substantial coverage, NomBank does not account for all withinsentence arguments and ignores extrasentential arguments altogether. These arguments, which we call implicit, are important to semantic processing, and their recovery could potentially benefit many NLP applications. We present a study of implicit arguments for a select group of frequent nominal predicates. We show that implicit arguments are pervasive for these predicates, adding 65% to the coverage of NomBank. | Beyond NomBank A Study of Implicit Arguments for Nominal Predicates Matthew Gerber and Joyce Y. Chai Department of Computer Science Michigan State University East Lansing Michigan USA gerberm2 jchai @ Abstract Despite its substantial coverage Nom-Bank does not account for all within-sentence arguments and ignores extra-sentential arguments altogether. These arguments which we call implicit are important to semantic processing and their recovery could potentially benefit many NLP applications. We present a study of implicit arguments for a select group of frequent nominal predicates. We show that implicit arguments are pervasive for these predicates adding 65 to the coverage of NomBank. We demonstrate the feasibility of recovering implicit arguments with a supervised classification model. Our results and analyses provide a baseline for future work on this emerging task. 1 Introduction Verbal and nominal semantic role labeling SRL have been studied independently of each other Carreras and Marquez 2005 Gerber et al. 2009 as well as jointly Surdeanu et al. 2008 Hajic et al. 2009 . These studies have demonstrated the maturity of SRL within an evaluation setting that restricts the argument search space to the sentence containing the predicate of interest. However as shown by the following example from the Penn TreeBank Marcus et al. 1993 this restriction excludes extra-sentential arguments 1 arg0 The two companies pred produce arg1 market pulp containerboard and white paper . The goods could be manufactured closer to customers saving pred shipping costs. The first sentence in Example 1 includes the PropBank Kingsbury et al. 2002 analysis of the verbal predicate produce where arg0 is the agentive producer and arg1 is the produced entity. The second sentence contains an instance of the nominal predicate shipping that is not associated with arguments in NomBank Meyers 2007 . From the sentences in Example 1 the reader can infer that The two companies refers to the