Dialogue systemsIn the SCHISMA project we investigate different possible architectures and techniques for building natural language dialogue systems. It serves as a motivation and testbed for various approaches and theories. SCHISMA is both the name of the project and the name of our prototype system: a dialogue system for theatre information and booking. The acronym is derived from the Dutch SCHouwburg Informatie Systeem. SCHISMA started as a joint research project of PTT Research and the Parlevink group of the University of Twente. The Twentse Schouwburg provides us with the necessary information to fill our database. The SCHISMA project has lead to publications, a prototype, a corpus and automatically generated grammars, work on spoken dialogue and various other activities related to dialogue systems, such as a virtual theatre and graduation work by students.
MotivationWe believe that natural language dialogue systems have several advantages over command-languages or graphical user interfaces. Natural language is natural to the user; no need to learn an austere command language or master the graphical interface controls. When using speech, it is even more natural. Moreover, speech technology opens the possibility to use the telephone for automatic information services. The use of dialogue, i.e. an interactive exchange of meaningful utterances, makes it possible to correct misunderstanding and recognition errors. In dialogue, circumstances and previous utterances play a role: the dialogue context. The context can be used, not only for disambiguation, but also to make information access more easy to use and more effective. Users can continue to ask queries about the previous topic. The system can remember user characteristics it has asked before.
The disadvantages of natural language interfaces have to be carefully dealt with. For instance, natural language interfaces do not naturally indicate the limits of the capacities and vocabulary of the system. Users will often be irritated by a missing functionality or unknown word. Such problems can however be overcome by a careful design of the systems `prompts' and thus manipulating the users perception of the system.
The application chosen for our prototype is a theatre information and booking service. The reason we choose theatre information, is that the domain is richer then the usual train- or airline information services. We could add all kinds of general knowledge about Shakespeare, Balanchine and so on. However, when restricted to the theatre schedule - what performance plays at what day - it can be constructed just as easily as the public transport information systems.
The second interesting feature of our application, is that it involves reservations. The user may reserve tickets for a particular performance. From the perspective of the system, a reservation requires a unique performance, a number of tickets and information on discount, preferred seats, as well as the name and identification number of the user. The user however, would first expect detailed information on the price and seats before giving his consent. We like to look at a reservation transaction as a promise of the user to pick up the tickets half an hour in advance and pay the price, given that the information the system provided was correct. In future we hope to extend the prototype into a system that is able to give advice or help the user make up his or her mind.
Corpus and Grammar
Building a dialogue system requires a corpus. The corpus gives insights into the behaviour of users and the typical expressions used in a particular domain. With a corpus the coverage of the lexicon and grammar can be evaluated and improved. In a Wizard-of-Oz experiment we collected a large sample of dialogues. The corpus is in Dutch and has been annotated and described. ( to the Corpus (zipped)).
Hugo ter Doest has generated a probabilistic unification grammar from the corpus. The corpus was tagged with syntactic categories and superficial structure. Unification constraints and probabilities were derived. The grammar was then tested on `seen' and `unseen' data from the same domain using a probabilistic left-corner parser for PATRII unification grammars. For more information see here or the list of publications (Ter Doest, 1998).
SCHISMA Prototype (THIS v 1.0)Try the SCHISMA Testapplet
Our current version of the SCHISMA system is called THIS v1.0 (THeatre Information System). It was build by Danny lie, Bas Leijdekkers and Eric Barten. The parser is based on a rewrite approach. The system has a simple agent architecture. Here is short description. For a more extensive description, see the list of publications (Lie et al 1997).
Virtual TheatreIn the SCHISMA project we investigate natural language dialogue systems in general. Dialogue is a natural way of accessing information. However, natural interaction is not necessarily restricted to speech or keyboard input. We are interested in other forms of communication as well. One such possibility, is the spatial metaphor: the user can make a virtual walk through the theatre. Inside the theatre information can be found at various locations. Information may be presented in the form of brochures, posters or in the form of an artificial agent Karin that is able to answer questions about performances and make reservations.
A virtual browser based on the VRML technology was developed by Richard Selles and Eduard Selles (Hogeschool Enschede, HIO). It contains the floor-plan of the Muziekcentrum building and various types of information related to theatre and music. At the moment, we are connecting the Karin agent interface to our SCHISMA prototype.
More information on the Virtual Theatre is available in Dutch. The VRML browser requires specific software and hardware. Here is a description of the system requirements and how to download them. Here is a list of screenshots from the Theatre.
Spoken Dialogue SystemsIn several student projects we acquired experience in building telephone-based dialogue systems for transactions, especially ticket reservation. Our experiences with the development toolkit, Speechmania, and some of our recommendations and conclusions can be found at Dialogue Systems for Reservation.
Other Theatre Information Systems...
PeopleThe following people are associated with the SCHISMA project.
Graduation workSCHISMA motivates a lot of student research. Here is a list of recent graduation projects on dialogue systems. For more on graduation projects, see our student information page.