Let D ={d1, d2, ...dD} be a given set of D string documents of total length n, our task is to index D, such that the k most relevant documents for an online query pattern P of length p can be retrieved efficiently. We propose an index of size |CSA|+ n logD(2 + o(1)) bits and O(ts(p)+k log log n+poly log log n) query time for the basic relevance metric term-frequency, where |CSA| is the size (in...

A k-query locally decodable code (LDC) C : Σn → ΓN encodes each message x into a codeword C(x) such that each symbol of x can be probabilistically recovered by querying only k coordinates of C(x), even after a constant fraction of the coordinates have been corrupted. Yekhanin (2008) constructed a 3-query LDC of subexponential length, N = exp(exp(O(log n/ log log n))), under the assumption that ...

We explore the problem of identifying and grouping information needs within a stream of queries. Our dataset contains sequences of queries issued by medical specialists to a domain-specific search system. Because the system allows for group logins, a sequence of queries could come from any number of specialists sharing an access point (for example, in an emergency room). We present several appr...

Hot standby systems often have to trade safety (i.e., not losing committed work) and freshness (i.e., having access to recent updates) for performance. Guaranteeing safety requires synchronous log shipping that blocks the primary until the log records are durably replicated in one or multiple backups; maintaining freshness necessitates fast log replay on backups, but is often defeated by the du...

In this paper we study privacy preservation for the publication of search engine query logs. In particular, we introduce a new privacy concern, which is that of website privacy (or business privacy). We define the possible adversaries that could be interested in disclosing website information and the vulnerabilities found in the query log, from which they could benefit. In this work we also det...

In this paper we consider the problem of computing the weak visibility polygon of any query line segment pq (or WVP(pq)) inside a given polygon P . Our first non-trivial algorithm runs in simple polygons and needs O(n log n) time and O(n) space in the preprocessing phase to report WVP(pq) of any query line segment pq in time O(log n + |WVP(pq)|). We also give an algorithm to compute the weak vi...

It’s an open secret that search engines collect detailed query logs, and sometimes release these data to third parties. While making this wealth of information available provides enormous opportunities for information retrieval and web mining research, it also raises serious concerns about the privacy of individuals. We strongly believe that this data should be published to allow researchers to...

Web search engines have changed our lives enabling instant access to information about subjects that are both deeply important to us, as well as passing whims. The search engines that provide answers to our search queries also log those queries, in order to improve their algorithms. Academic research on search queries has shown that they can provide valuable information on diverse topics includ...

We propose a new approach for implementing P-log using XASP, the interface of XSB with Smodels. By using the tabling mechanism of XSB, our system is most of the times faster than P-log. In addition, our implementation has query features not supported by P-log, as well as new set operations for domain definition.