Signature file methods for implementing a ranking strategy

In this paper we present two partitioning methods for signature files in order to implement the tf × idf ranking strategy efficiently. The methods represent term frequencies without storing them explicitly. The first method partitions terms in a document based upon their term frequencies. The second one further partitions the terms vertically based upon their ordinal numbers in the dictionary. The latter allows partial retrieval of the signature files in response to a query. A fast weight computation method is also described. Detailed analysis of the new methods is given. Experimental runs are performed on the document collections made available with the SMART system.