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The LIMSI (Laboratoire d'Informatique pour la Mecanique et les Sciences de l'Ingenieur) ARISE (Automatic Railway Information Systems for Europe) system provides vocal access to rail travel information for main French intercity connections, including timetables, simulated fares and reservations, reductions and services. Our goal is to obtain high dialogue success rates with a very open structure, where the user is free to ask any question or to provide any information at any point in time. In order to improve the performance with such an open dialogue strategy, we make use of implicit confirmation using the caller's wording (when possible) and change to a more constrained dialogue level when the dialogue is not going well. The same system architecture is being used to develop a French/English prototype timetable service for high-speed trains between Paris and London.
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Lamel et al. (2002) studied this question.
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