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Data exchange: semantics and query answering
- Ronald Fagin, Phokion G. Kolaitis, Renée J. Miller, Lucian Popa
- Computer ScienceTheor. Comput. Sci.
- 8 January 2003
This paper gives an algebraic specification that selects, among all solutions to the data exchange problem, a special class of solutions that is called universal and shows that a universal solution has no more and no less data than required for data exchange and that it represents the entire space of possible solutions.
Composing schema mappings: second-order dependencies to the rescue
- Ronald Fagin, Phokion G. Kolaitis, Lucian Popa, W. Tan
- Computer Science, MathematicsPODS '04
- 14 June 2004
It is shown that the composition of finite sets of source-to-target tgds is always definable by a second-order tgd, and that second-orders possess good properties for data exchange, and introduces a class of existential second- order formulas with function symbols, which are made a case that they are the "right" language for composing schema mappings.
Data exchange: getting to the core
This work considers the well-known notion of the core of a structure, a notion that was first studied in graph theory, but has also played a role in conjunctive-query processing, and shows that this core is also a universal solution, and hence the smallest universal solution.
On the Decision Problem for Two-Variable First-Order Logic
- E. Grädel, Phokion G. Kolaitis, Moshe Y. Vardi
- Mathematics, Computer ScienceBulletin of Symbolic Logic
- 1 March 1997
Improve Mortimer's bound by one exponential and show that every satisfiable FO2-sentence has a model whose size is at most exponential in the size of the sentence, establishing that the satisfiability problem for FO2 is NEXPTIME-complete.
Conjunctive-query containment and constraint satisfaction
This paper examines the tractable cases of Boolean constraint-satisfaction problems and shows that they do uniformize, and exhibits three nonuniform tractability results that uniformize and give rise to polynomial-time solvable cases of constraint satisfaction and conjunctive-query containment.
Finite Model Theory and Its Applications
- E. Grädel, Phokion G. Kolaitis, S. Weinstein
- Computer ScienceTexts in Theoretical Computer Science. An EATCS…
- 24 April 2007
Themes in Finite Model Theory and Descriptive Complexity, Logic and Random Structures, Embedded Finite Models and Constraint Databases, and Local Variations on a Loose Theme.
On the expressive power of datalog: tools and a case study
It is shown here that the two dichotomies are indeed proper in terms of expressibility in Datalog(≠), and the expressibility of fixed subgraph homeomorphism queries on directed graphs is classified.
Schema mappings, data exchange, and metadata management
- Phokion G. Kolaitis
- Computer SciencePODS '05
- 13 June 2005
The main aim in this paper is to present an overview of recent advances in data exchange and metadata management, where the schema mappings are between relational schemas.
Repair checking in inconsistent databases: algorithms and complexity
A polynomial-time algorithm is given for subset-repair checking under integrity constraints that are the union of a weakly acyclic set of local-as-view (LAV) tuple-generating dependencies and a set of equality-generate dependencies and it is shown that the aforementioned tractability results are optimal and cardinality-based repairs is a coNP-complete problem.
The Connectivity of Boolean Satisfiability: Computational and Structural Dichotomies
The results assert that the intractable side of the computational dichotomies is PSPACE-complete, while the tractable side—which includes but is not limited to all problems with polynomial-time algorithms for satisfiability—is in P for the $st$-connectivity question, and in coNP for the connectivity question.