Improving disambiguation in FASIT

An improved disambiguation mechanism, based on a recursive transition network, was used to enhance the automatic indexing system FASIT. FASIT with both the recursive transition network and alone showed improvement over single‐term indexing in retrieval experiment with a medical test collection. However, FASIT with the enhanced disambiguation mechanism did not provide any noticeable improvement over FASIT alone. The failure of FASIT with the recursive transition network to improve upon the retrieval results of FASIT alone appeared to be due partly to the stepwise reduction of the effectiveness of further disambiguation in the FASIT environment. This factor was examined in a second experiment, which tested the effects of a perfect diambiguation mechanism on retrieval based on indexing representations provided by FASIT. Again, the difference in retrieval performance between FASIT alone and with a perfect disambiguation was minimal. The results corroborate the findings of the earlier experiment, which showed that retrieval performance is not noticeably affected by improvements to FASIT's disambiguation process. This experiment provides evidence that little improvement in retrieval performance can be expected, regardless of the degree of which FASIT's disambiguation mechanism alone is enhanced. Future research with FASIT should focus on other areas, such as refinements in concept selection and concept grouping and the incorporation of semantic information. © 1992 John Wiley & Sons, Inc.