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Natural Language Dialogue Service

for Appointment Scheduling Agents?

Stephan Busemann, Thierry Declerck, Abdel Kader Diagne,

Luca Dini, Judith Klein, Sven Schmeier


Stuhlsatzenhausweg 3, 66123 Saarbr?ucken, Germany

[email protected]


Appointment scheduling is a problem faced daily by many individuals and organizations. Cooperating agent systems have been developed to partially automate this task. In order to extend the circle of participants as far as possible we advocate the use of natural language transmitted by email. We describe Cosma, a fully implemented German language server for existing appointment scheduling agent systems. Cosma can cope with multiple dialogues in parallel, and accounts for differences in dialogue behaviour between human and machine agents. NL coverage of the sublanguage is achieved through both corpusbased grammar development and the use of message extraction techniques.

1 Motivation

Appointment scheduling is a problem faced daily by many individuals and organizations, and typically solved using communication in natural language (NL) by phone, fax or by mail. In general, cooperative interaction between several participants is required. Since appointments are often scheduled only after a sequence of point-to-point connections this will, at times, necessitate repeated rounds of communication until all participants agree to some date and place. This is a very time-consuming task that should be automated.

Systems available on the market allow for calendar and contact management. As (Busemann and Merget, 1995) point out in a market survey, all planning and scheduling activity remains with the user. Cooperative agent systems developed in the field of Distributed AI are designed to account for the scheduling tasks. Using distributed rather than centralized

?This work has been supported by a grant from the German Federal Ministry of Education, Science, Research and Technology (FKZ ITW-9402).

calendar systems, they not only guarantee a maximum privacy of calendar information but also offer their services to members or employees in external organizations. Although agent systems allow users to automate their scheduling tasks to a considerable degree, the circle of participants remains restricted to users with compatible systems.

To overcome this drawback we have designed and implemented Cosma, a novel kind of NL dialogue systems that serves as a German language frontend system to scheduling agents. Human language makes agent services available to a much broader public. Cosma allows human and machine agents to participate in appointment scheduling dialogues via e-mail. We are concerned with meetings all participants should attend and the date of which is negotiable.

2 Design guidelines

Cosma is organized as a client/server architecture. The server offers NL dialogue service to multiple client agent systems. Up to now, three different types of agent systems have been hooked up to the NL server. Agents developed in-house were used for the early system described in (Busemann et al., 1994). In a subsequent version, the MEKKA agents developed by Siemens AG (Lux et al., 1992) have been adapted. We present in Section 4 a third kind of client system, the PASHA II user agent.

Given the use of distributed calendar systems, techniques used by both human and machine agents for cooperatively scheduling appointments must be based on negotiation dialogues. However, human dialogue behaviour differs from interaction between machine agents considerably, as will be discussed in Section 4. A human-machine interface to existing appointment scheduling agent systems should comply to the following requirements:

ffl Human utterances must be analyzed to correspond closely to agent actions.

ffl Machine utterances must conform to human dialogue strategies.