A Flexible Architecture for Reference Resolution

Proceedings of EACL '99 A Flexible Architecture for Reference Resolution Donna K. Byron and Joel R. Tetreault Department of Computer Science University of Rochester Rochester NY 14627, U.S.A. dbyron/tetreaul@cs, rochester, edu Abstract This paper describes an architecture for performing anaphora resolution in a flexible way. Systems which con- form to these guidelines are well- encapsulated and portable, and can be used to compare anaphora resolu- tion techniques for new language un- derstanding applications. Our im- plementation of the architecture in a pronoun resolution testing platform demonstrates the flexibility of the ap- proach. 1 Introduction When building natural language understand- ing systems, choosing the best technique for anaphora resolution is a challenging task. The system builder must decide whether to adopt an existing technique or design a new approach. A huge variety of techniques are described in the literature, many of them achieving high suc- cess rates on their own evaluation texts (cf. Hobbs 1986; Strube 1998; Mitkov 1998). Each technique makes different assumptions about the data available to reference resolution, for ex- ample, some assume perfect parses, others as- sume only POS-tagged input, some assume se- mantic information is available, etc. The chances are high that no published technique will ex- actly match the data available to a particular sys- tem's reference resolution component, so it may The authors thank James Allen for help on this project, as well as the anonymous reviewers for helpful comments on the paper. This material is based on work supported by USAF/Rome Labs contract F30602-95-1-0025, ONR grant N00014-95-1 - 1088, and Columbia Univ. grant OPG: 1307. 229 not be apparent which method will work best. Choosing a technique is especially problematic for designers of dialogue systems trying to pre- dict how anaphora resolution techniques devel- oped for written monologue will perform when adapted for spoken dialogue. In an ideal world, the system designer would implement and com- pare many techniques on the input data available in his system. As a good software engineer, he would also ensure that any pronoun resolution code he implements can be ported to future ap- plications or different language domains without modification. The architecture described in this paper was designed to provide just that functionality. Anaphora resolution code developed within the architecture is encapsulated to ensure portabil- ity across parsers, language genres and domains. Using these architectural guidelines, a testbed system for comparing pronoun resolution tech- niques has been developed at the University of Rochester. The testbed provides a highly config- urable environment which uses the same pronoun resolution code regardless of the parser front-end and language type under analysis. It can be used, inter alia, to compare anaphora resolution tech- niques for a given application, to compare new techniques to published baselines, or to compare a particular technique's performance across lan- guage types. 2 The Architecture 2.1 Encapsulation of layers Figure 1 depicts the organization of the architec- ture. Each of the three layers have different re- sponsibilities: Proceedings of EACL '99 Layer 1: Supervisor layer controls which …

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