Abstract. We study containment of conjunctive queries that are evaluated over databases that may contain tuples with null values. We assume the semantics of SQL for single block qu...
Cryptographic techniques for reasoning about information leakage have recently been brought to bear on the classical problem of statistical disclosure control – revealing accurat...
We consider random graphs, and their extensions to random structures, with edge probabilities of the form βn−α , where n is the number of vertices, α, β are fixed and α >...
Abstract. Consistent query answering (CQA) is an approach to querying inconsistent databases without repairing them first. This invited talk introduces the basics of CQA, and disc...
The first aim of this paper is to present the logical core of XPath 2.0: a logically clean, decidable fragment, which includes most navigational features of XPath 2.0 (complex co...
Abstract. Information concerning the origin of data (that is, its provenance) is important in many areas, especially scientific recordkeeping. Currently, provenance information mu...
Close relationships between XML navigation and temporal logics have been discovered recently, in particular between logics LTL and CTL⋆ and XPath navigation, and between the µ-c...
Abstract. In many cases, users may want to consider incomplete answers to their queries. Often, however, there is an overwhelming number of such answers, even if subsumed answers a...
We consider several private database query problems. The starting point of this work is the element rank problem: the server holds a database of n integers, and the user an integer...