Interactive Problem Solving and Dialogue in the ATIS Domain

Interactive Problem Solving and Dialogue in the ATIS Domain 1 Stephanie Seneff, Lynette Hirschman, and Victor W. Zue Spoken Language Systems Group Laboratory for Computer Science Massachusetts Institute of Technology Cambridge, Massachusetts 02139 ABSTRACT This paper describes the present status of the discourse and dialogue models within the MIT ATIS system, extended to sup- port the notion of booking a flight. The discourse model includes not only the resolution of explicit anaphoric references, but also indirect and direct references to information mentioned earlier in the conversation, such as a direct reference to an entry in a previ- ously displayed table or an indirect reference to a date, as in "the following Thursday." The system keeps a history table containing objects such as flights and dates, represented as semantic frames, as well as the active ticket, previously booked tickets, and previ- ously displayed tables. During flight reservations scenarios, the system monitors the state of the ticket (which is displayed to the user), making sure that all information is complete (by querying the user) before allowing a booking. It may even initiate calls to the database to provide additional unsolicited information as ap- propriate. We have collected several dialogues of subjects using the system to make reservations, and from these, we are learning how to design better dialogue models. INTRODUCTION A key goal of spoken language systems is to provide sup- port for interactive problem solving. To be effective in this role, a system should permit the user to build up a solution incrementally, and therefore to make implicit and explicit ref- erence to information from earlier parts of the system/user dialogue. In addition, in certain scenarios, e.g., making flight reservations, it is natural to have the system play an ac- tive role in the dialogue. It is in fact our belief that spoken language systems will never reach a practical level of perfor- mance unless special attention is paid to issues of discourse and dialogue. To this end, we spent considerable effort over the last several months augmenting our system's discourse capabilities, and developing a much more active role for the computer during the dialogue with a user. We can view interactive problem solving systems on a continuum of system/user control. At one extreme would be a system that answers user's questions without at any point 1This research was supported by DARPA under Contract N00014- 89-J-1332, monitored through the Office of Naval Research. asking questions or making suggestions. At the other extreme would be a menu system that forces the user into a very limited range of choices. This paper will describe an attempt at MIT to explore a middle ground in this continuum, in the context of allowing users to make flight reservations. There are a number of advantages to an approach which explores a mixed initiative system for flight reservations. First, it provides the user with a more focused way to interact: making a reservation provides a natural notion of task com- pletion. Second , a system that can …

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