UNISYS: Description Of The UNISYS System Used For MUC-3


This paper describes the Unisys MUC-3 text understanding system, a system based upon a three-tiered approach to text processing in which a powerful knowledge-based form of information retrieval plays a central role. This knowledge-based form of information retrieval makes it possible to define an effective level of text analysis that falls somewhere between what is possible with standard keyword-based information retrieval techniques and deep linguistic analysis. The Unisys Center for Advanced Information Technology (CAIT) has a long-standing commitment to NLP research and development, with the Pundit NLP system developed at CAIT serving as the Center's primary research vehicle [3]. The Unisys MUC-3 system, however, consists primarily of components that are less than 7 months old and still in a developmental stage. Although the three-tiered processing approach that the MUC-3 system's architecture is based upon includes Pundit as its third level of (linguistic) analysis, the incorporation of Pundit into the MUC-3 system was not achieved in time for the final MUC-3 test in May 1991. A decision was made to focus on the development of a knowledge-based information retrieval component, and this precluded the integration of Pundit into the prototype.