Managing information at linguistic interfaces

Managing information at linguistic interfaces* Johan Bos and C.J. Rupp Computerlinguistik Universit~it des Saarlandes D-66041 Saarbrticken {bos, cj }©coli. uni-sb, de Bianka Buschbeck-Wolf and Michael Dorna Institut ftir Maschinelle Sprachverarbeitung (IMS) Universit~it Stuttgart D-70174 Stuttgart {bianka, michl}~ims .uni-stuttgart. de Abstract A large spoken dialogue translation system imposes both engineering and linguistic constraints on the way in which linguistic information is communi- cated between modules. We describe the design and use of interface terms, whose formal, functional and communicative role has been tested in a sequence of integrated systems and which have proven adequate to these constraints. 1 Introduction This paper describes the development and usage of interface representations for linguistic informa- tion within the Verbmobil project: a large dis- tributed project for speech-to-speech translation of negotiation dialogues, between English, German and Japanese. We take as our reference point the Verbmobil Research Prototype (Bub et al., 1997), but this is only one of a sequence of fully integrated running systems. The functional, formal and com- municative role of interface terms within these sys- tems, once instigated, has already been maintained through changes in the overall architecture and con- stitution of the Verbmobil consortium. There are two aspects to our story: • the practical and software engineering con- straints imposed by the distributed develop- ment of a large natural language system. • the linguistic requirements of the translation task at the heart of the system. * This work was funded by the German Federal Ministry of Education, Science, Research and Technology (BMBF) in the framework of the Verbmobil project under grant 01 IV 701 R4 and 01 IV 701 N3. The responsibility for this article lies with the authors. Thanks to our many Verbmobil colleagues who helped to design and develop the results presented here, and also to the anonymous reviewers for giving useful hints to improve this paper. The prominence of the engineering requirements is further heightened by the fact that we are dealing with a spoken dialogue system which must strive towards real time interactions. We proceed by describing the requirements of the Verbmobil Research Prototype, the actual contents of the Verbmobil Interface Term (henceforth VIT), the semantic formalism encoded within VITs and processing aspects. We conclude that VITs fulfill the joint goals of a functional interface term and an adequate linguistic representation within a single data structure. 1.1 Modularity We are concerned here with the interface represen- tations exchanged between modules that make use of traditional linguistic concepts. Figure 1 shows a simplified form of the Verbmobil Research Proto- type architecture 1 , the modules in the grey shaded area make use of VITs as linguistic interface terms and are loosely termed the "linguistic" modules of the system, in contrast to the other modules shown which are chiefly concerned with the processing of acoustic signals. The linguistic design criteria for VITs derive mainly from the syntactic and seman- tic analysis module, labelled SynSem, the generation and the transfer modules. One point that should be made at the outset is …

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