A Unified Representation for Morphological, Syntactic, Semantic, and Referential Annotations

Proceedings of the Workshop on Frontiers in Corpus Annotation II: Pie in the Sky, pages 13–20, Ann Arbor, June 2005. c⃝2005 Association for Computational Linguistics A Unified Representation for Morphological, Syntactic, Semantic, and Referential Annotations Erhard W. Hinrichs, Sandra Kübler, Karin Naumann SfS-CL, University of Tübingen Wilhelmstr. 19 72074 Tübingen, Germany {eh,kuebler,knaumann}@sfs.uni-tuebingen.de Abstract This paper reports on the SYN-RA (SYNtax-based Reference Annotation) project, an on-going project of annotating German newspaper texts with referential relations. The project has developed an in- ventory of anaphoric and coreference rela- tions for German in the context of a uni- fied, XML-based annotation scheme for combining morphological, syntactic, se- mantic, and anaphoric information. The paper discusses how this unified annota- tion scheme relates to other formats cur- rently discussed in the literature, in par- ticular the annotation graph model of Bird and Liberman (2001) and the pie-in-the- sky scheme for semantic annotation. 1 Introduction The purpose of this paper is threefold: (i) it dis- cusses an annotation scheme for referential relations for German that is significantly broader in scope than existing schemes for the same task and lan- guage and that also goes beyond the inventory of anaphoric relations included in the pie-in-the-sky sample feature structures1, (ii) it presents a unified, XML-based annotation scheme for combining mor- phological, syntactic, semantic, and anaphoric infor- mation, and (iii) it discusses how this unified anno- tation scheme relates to other formats currently dis- cussed in the literature, in particular the annotation 1See e.g. nlp.cs.nyu.edu/meyers/pie-in-the-sky/ analysis5. graph model of Bird and Liberman (2001) and the pie-in-the-sky scheme for semantic annotation2. 2 Referential Relations This section introduces the inventory of referential relations adopted in the SYN-RA project. We define referential relations as a cover-term for all contex- tually dependent reference relations. The inventory of such relations adopted for SYN-RA is inspired by the annotation scheme first developed in the MATE project (Davies et al., 1998). However, it takes a cautious approach in that it only adopts those refer- ential relations from MATE for which the develop- ers of MATE report a sufficiently high level of inter- annotator agreement (Poesio et al., 1999). SYN-RA currently uses the following subset of relations: coreferential, anaphoric, cataphoric, bound, split antecedent, instance, and expletive. The potential markables are definite NPs, personal pro- nouns, relative, reflexive, and reciprocal pronouns, demonstrative, indefinite and possessive pronouns. There is a second research effort under way at the European Media Laboratory Heidelberg, which also annotates German text corpora and dialog data with referential relations. Since their corpora are not pub- licly available, it is difficult to verify their inventory of referential relations. Kouchnir (2003) has used their data and describes the relations anaphoric, coreferential, bridging, and none. Following van Deemter and Kibble (2000), we define a coreference relation to hold between two 2See nlp.cs.nyu.edu/meyers/pie-in-the-sky/ pie-in-the-sky-descript.html. 13 NPs just in case they refer to the same extra- linguistic referent in the real world. In the following example, a coreference relation exists between the noun phrases [1] and [2], and an anaphoric …

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