Abstract

We describe a data structure that uses O (n)-word space and reports k most relevant documents that contain a query pattern P in optimal O(|P| + k) time. Our construction supports an ample set of important relevance measures, such as the frequency of P in a document and the minimal distance between two occurrences of P in a document. We show how to reduce the space of the data structure from O(n log n) to O (n(log ? + log D + log log n)) bits, where ? is the alphabet size and D is the total number of documents. Copyright © SIAM.