Description of the LINK system used for MUC-4

The University of Michigan's natural language processing system, called LINK, is a unification-based system which we have developed over the last four years. Prior to MUC-4, LINK had been used to extract information from free-form texts in two narrow application domains. One application corpus contained terse descriptions of symptoms displayed by malfunctioning automobiles, and the repairs which fixed them. The other corpus described sequences of activities to be performed on an assembly line. In empirical testing in these two domains, LINK correctly processed 70% of previously unseen descriptions. A template was counted as correct only if all of the fillers in the template were filled correctly. In addition, LINK generated incomplete (but not incorrect) templates for another 15% of the descriptions.