PEGASUS: A Spoken Language Interface for On-Line Air Travel Planning

PEGASUS: A Spoken Language Interface for On-Line Air Travel Planning I Victor Zue, Stephanie Seneff, Joseph Polifroni, Michael Phillips Christine Pao, David Goddeau, and James Glass, and Eric Brill 2 Spoken Language Systems Group Laboratory for Computer Science Massachusetts Institute of Technology Cambridge, Massachusetts 02139 ABSTRACT This paper describes PEGASUS, a spoken language inter- face for on-line air travel planning that we have recently devel- oped. PEGASUS leverages off our spoken language technology development in the ATIS domain, and enables users to book flights using the American Airlines EAASY SABRE system. The input query is transformed by the speech understanding sys- tem to a frame representation that captures its meaning. The tasks of the System Manager include transforming the seman- tic representation into an EAASY SABRE command, transmit- ting it to the application backend, formatting and interpreting the xesulting information, and managing the dialogue. Pre- liminary evaluation results suggest that users can learn to make productive use of PEGASUS for travel planning, although much work remains to be done. INTRODUCTION Over the past few years, our group has participated, as a member of the ARPA Human Language Technology (HLT) research community, in the development of spo- ken language technology in the common domain called Air Travel Information Service, or ATIS [i]. ATIS permits users to verbally query for air travel information, such as flight schedules from one city to another, obtained from a small relational database excised from the Official Air- line Guide. By requiring that all system developers use the same database, it has been possible to compare the performance of various spoken language systems based on their ability to extract the correct information from the database, using a set of prescribed training and test data, and a set of interpretation guidelines. Indeed, pe- riodic common evaluations have occurred at regular in- tervals, and steady performance improvements have been observed for all systems [2, 3, 4]. While the ATIS task has been instrumental in the de- velopment of technologies that can understand sponta- neously generated verbal queries in a limited domain, it 1This research was supported by ARPA under Contract N00014- 89-J-1332, monitored through the Office of Naval Research. 2The authors are listed in reversed alphabetical order. does have some shortcomings. First, the current com- mon evaluation focuses on the correctness of the infor- mation extracted from the database without any regard to the system's side of the interchange (e.g., clarifica- tion queries and helpful suggestions). Thus it has the effect of discouraging research on dialogue-based systems which, we believe, is a crucial aspect of human com- puter interactions. Second, ATIS makes use of a mock-up, static database containing flight and fare information for a small set of cities within the United States and Canada. It is not a realistic model of the databases actually be- ing used by travel agents and travellers. In particular, operational flight information systems are much larger and more complex, and, most impoi'tantly, they contain information which is dynamic in nature. The rapid technological …

Content truncated to 500 words