Leopoldo E. Bertossi

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In this paper we consider the problem of the logical characterization of the notion of consistent answer in a relational database that may violate given integrity constraints. This notion is captured in terms of the possible repaired versions of the database. A method for computing consistent answers is given and its soundness and completeness (for some(More)
A relational database is inconsistent if it does not satisfy a given set of integrity constraints. Nevertheless, it is likely that most of the data in it is consistent with the constraints. In this paper we apply logic programming based on answer sets to the problem of retrieving consistent information from a possibly inconsistent database. Since consistent(More)
For several reasons databases may become inconsistent with respect to a given set of integrity constraints (ICs): (a) The DBMS have no mechanism to maintain certain classes of ICs. (b) New constraints are imposed on preexisting, legacy data. (c) The ICs are soft, user, or informational constraints that are considered at query time, but without being(More)
vi Artificial intelligence continues to be one of the most vibrant, challenging, and forward-looking areas of computer science. These proceedings collect the papers accepted for presentation at the Twenty-first International Joint Conference on Artificial Intelligence (IJCAI-09) held in Pasadena, California, USA from July 11–17, 2009. This collection(More)
We consider here scalar aggregation queries in databases that may violate a given set of functional dependencies. We define consistent answers to such queries to be greatest lowest/least upper bounds on the value of the scalar function across all (minimal) repairs of the database. We show how to compute such answers. We provide a complete characterization(More)
Matching dependencies were recently introduced as declarative rules for data cleaning and entity resolution. Enforcing a matching dependency on a database instance identifies the values of some attributes for two tuples, provided that the values of some other attributes are sufficiently similar. Assuming the existence of matching functions for making two(More)
In this chapter, we summarize the research on querying inconsistent databases we have been conducting over the last five years. The formal framework we have used is based on two concepts: repair and consistent query answer. We describe different approaches to the issue of computing consistent query answers: query transformation, logic programming, inference(More)
Inconsistency arises in many areas in advanced computing. Examples include: Merging information from heterogeneous sources; Negotiation in multi-agent systems; Understanding natural language dialogues; and Commonsense reasoning in robotics. Often inconsistency is unwanted, for example, in the specification for a plan, or in sensor fusion in robotics. But(More)
This chapter provides a predicate logic based semantics for active rules in active databases [18, 9]. Our main contribution is a proposal to integrate the specification of active rules with the specification of the dynamics of transaction based change in relational databases. Our approach extends previous work in which the situation calculus, a language of(More)