Date of Award


Degree Name

Master of Science


Computer Science

First Advisor

Dr. Dionysios Kountanis

Second Advisor

Dr. Dalia Motzkin

Access Setting

Masters Thesis-Open Access


In processing a Boolean query against a non-inverted file, a subset of the query's keys must be selected. Only the records satisfying these keys need to be retrieved from the file. A dynamic programming algorithm, the Dual-to-minDF, is developed here for arriving at the optimum set of keys, i.e., the minimum number of external record retrievals. Previously suggested greedy methods yield feasible solutions which may or may not be optimal. This algorithm has exponential time complexity. However, it is useful for applications involving relatively short queries with duplication of keys within different conjuncts, and in cases where the files have large numbers of records per keyword. This makes the trade-off of I/o savings vs. extra processing costs worth it. Possible extensions of this research are suggested.