We show that all–instances termination of chase is undecidable. More precisely, there is no algorithm deciding, for a given set T consisting of Tuple Generating Dependencies (a.k.a. Datalog program), whether the T -chase on D will terminate for every finite database instance D. Our method applies to Oblivious Chase, Semi-Oblivious Chase and – after a slight modification – also for Standard Chas...

We show that all–instances termination of chase is undecidable. More precisely, there is no algorithm deciding, for a given set T consisting of Tuple Generating Dependencies (a.k.a. Datalog program), whether the T -chase on D will terminate for every finite database instance D. Our method applies to Oblivious Chase, Semi-Oblivious Chase and – after a slight modification – also for Standard Chas...

The chase procedure and its applications Adrian Constantin Onet, Ph.D. Concodria University, 2012 The goal of this thesis is not only to introduce and present new chasebased algorithms, but also to investigate the differences between the main existing chase procedures. In order to achieve this, first we will investigate and do a clear delimitation between the existing chase algorithms based on ...

Several database areas such as data exchange and integra-tion share the problem of fixing database instance viola-tions with respect to a set of constraints. The chase al-gorithm solves such violations by inserting tuples and set-ting the value of nulls. Unfortunately, the chase algorithmmay not terminate and the problem of deciding whether thechase process terminates is...

We investigate the implication problem for constrained tuple-generating dependencies (CTGDs), the extension of tuple-and equality-generating dependencies that permits expression of semantic relations (constraints) on variables. The implication problem is central to identifying redundant integrity constraints, checking integrity constraints on constraint databases, detecting the independence of ...

A lot of research activity has recently taken place around the chase procedure, due to its usefulness in data integration, data exchange, query optimization, peer data exchange and data correspondence, to mention a few. As the chase has been investigated and further developed by a number of research groups and authors, many variants of the chase have emerged and associated results obtained. Due...

In recent work, Salimi and Bertossi provide a tight connection between causality and tuple-based data repairs. We investigate this connection between causality and two other kinds of repair models. First, we consider cell-based V -repairs, i.e., repairs that are obtained by modifying cells in the data. In contrast, tuple-based repairs only allow for the deletion of tuples. Second, we introduce ...