Dagstuhl Seminar Proceedings, Volume 6401



Publication Details

  • published at: 2006-11-15
  • Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik

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06401 Abstracts Collection – Complexity of Constraints

Authors: Nadia Creignou, Phokion Kolaitis, and Heribert Vollmer


Abstract
From 01.10.06 to 06.10.06, the Dagstuhl Seminar 06401 ``Complexity of Constraints'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.

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Nadia Creignou, Phokion Kolaitis, and Heribert Vollmer. 06401 Abstracts Collection – Complexity of Constraints. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{creignou_et_al:DagSemProc.06401.1,
  author =	{Creignou, Nadia and Kolaitis, Phokion and Vollmer, Heribert},
  title =	{{06401 Abstracts Collection – Complexity of Constraints}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--14},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.1},
  URN =		{urn:nbn:de:0030-drops-8067},
  doi =		{10.4230/DagSemProc.06401.1},
  annote =	{Keywords: Constraint satisfaction problems, computational complexity, universal algebra, mathematical logic, finite model theory}
}
Document
06401 Executive Summary – Complexity of Constraints

Authors: Nadia Creignou, Phokion Kolaitis, and Heribert Vollmer


Abstract
In this document we describe the original motivation and goals of the seminar as well as the sequence of talks given during the seminar.

Cite as

Nadia Creignou, Phokion Kolaitis, and Heribert Vollmer. 06401 Executive Summary – Complexity of Constraints. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-6, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{creignou_et_al:DagSemProc.06401.2,
  author =	{Creignou, Nadia and Kolaitis, Phokion and Vollmer, Heribert},
  title =	{{06401 Executive Summary – Complexity of Constraints}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--6},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.2},
  URN =		{urn:nbn:de:0030-drops-8001},
  doi =		{10.4230/DagSemProc.06401.2},
  annote =	{Keywords: Constraint satisfaction problems, complexity}
}
Document
A Unifying Theory of Structural Decompostions for the Constraint Satisfaction Problems

Authors: David Cohen, Marc Gyssens, and Peter Jeavons


Abstract
In this talk (draft paper) we develop the theory of structural decompositions for the CSP. We begin with the very general notion of a guarded decomposition and make several simplifying assumptions to arrive a the definition of an acyclic guarded cover. We show how many existing decompositions can seen as acyclic guarded covers. We develop a generic algorithm for discovering acyclic guarded covers under the further assumption that they have a join tree satisfying a simple extra condition. We show that many existing decompositions do in fact satisfy this extra condition. Using this theory we are able to describe a new class of structural decompostion which we call spread cuts. These generalise many existing decomposition methods. We present a class of hypergraphs whose spread cut width is significantly smaller than their hypertree width. The definition of a guarded decomposition and the algorithm for discovering them were motvated by the similar algorithms developed by Gottlob, Scarcello and Leone in their work on hypertrees. The authors also wish to acknowledge that an acyclic guarded decomposition is very similar to a generalised hypertree decomposition as described in the hypertree literature.

Cite as

David Cohen, Marc Gyssens, and Peter Jeavons. A Unifying Theory of Structural Decompostions for the Constraint Satisfaction Problems. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{cohen_et_al:DagSemProc.06401.3,
  author =	{Cohen, David and Gyssens, Marc and Jeavons, Peter},
  title =	{{A Unifying Theory of Structural Decompostions for the Constraint Satisfaction Problems}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--22},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.3},
  URN =		{urn:nbn:de:0030-drops-8017},
  doi =		{10.4230/DagSemProc.06401.3},
  annote =	{Keywords: Structural decomposition, spread cut}
}
Document
Constraint satisfaction problems in clausal form: Autarkies, minimal unsatisfiability, and applications to hypergraph inequalities

Authors: Oliver Kullmann


Abstract
Generalised CNFs are considered using such literals, which exclude exactly one possible value from the domain of the variable. First we consider poly-time SAT decision (and fixed-parameter tractability) exploiting matching theory. Then we consider irredundant generalised CNFs, and characterise some extremal minimally unsatisfiable CNFs.

Cite as

Oliver Kullmann. Constraint satisfaction problems in clausal form: Autarkies, minimal unsatisfiability, and applications to hypergraph inequalities. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{kullmann:DagSemProc.06401.4,
  author =	{Kullmann, Oliver},
  title =	{{Constraint satisfaction problems in clausal form: Autarkies, minimal unsatisfiability, and applications to hypergraph inequalities}},
  booktitle =	{Complexity of Constraints},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.4},
  URN =		{urn:nbn:de:0030-drops-8030},
  doi =		{10.4230/DagSemProc.06401.4},
  annote =	{Keywords: Signed CNF, autarkies, minimal unsatisfiable, hypergraph colouring, block designs}
}
Document
Constraint Satisfaction with Succinctly Specified Relations

Authors: Hubie Chen and Martin Grohe


Abstract
The general intractability of the constraint satisfaction problem has motivated the study of the complexity of restricted cases of this problem. Thus far, the literature has primarily considered the formulation of the CSP where constraint relations are given explicitly. We initiate the systematic study of CSP complexity with succinctly specified constraint relations. This is joint work with Hubie Chen.

Cite as

Hubie Chen and Martin Grohe. Constraint Satisfaction with Succinctly Specified Relations. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{chen_et_al:DagSemProc.06401.5,
  author =	{Chen, Hubie and Grohe, Martin},
  title =	{{Constraint Satisfaction with Succinctly Specified Relations}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--15},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.5},
  URN =		{urn:nbn:de:0030-drops-8022},
  doi =		{10.4230/DagSemProc.06401.5},
  annote =	{Keywords: Constraint satisfaction, complexity, succinct representations}
}
Document
Enumerating all Solutions for Constraint Satisfaction Problems

Authors: Henning Schnoor and Ilka Schnoor


Abstract
We contribute to the study of efficient enumeration algorithms for all solutions of constraint satisfaction problems. The only algorithm known so far, presented by Creignou and Hébrard and generalized by Cohen, reduces the enumeration problem for a constraint language $Gamma$ to the decision problem for a slightly enlarged constraint language $Gamma^+,$ i.e., it yields an efficient enumeration algorithm for the case where $mathrm{CSP}(Gamma^+)$ is tractable. We develop a new class of algorithms, yielding efficient enumeration algorithms for a broad class of constraint languages. For the three-element domain, we achieve a first step towards a dichotomy theorem for the enumeration problem.

Cite as

Henning Schnoor and Ilka Schnoor. Enumerating all Solutions for Constraint Satisfaction Problems. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{schnoor_et_al:DagSemProc.06401.6,
  author =	{Schnoor, Henning and Schnoor, Ilka},
  title =	{{Enumerating all Solutions for Constraint Satisfaction Problems}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--25},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.6},
  URN =		{urn:nbn:de:0030-drops-8040},
  doi =		{10.4230/DagSemProc.06401.6},
  annote =	{Keywords: Complexity, constraint satisfaction, enumeration}
}
Document
New Algebraic Tools for Constraint Satisfaction

Authors: Henning Schnoor and Ilka Schnoor


Abstract
The Galois correspondence involving polymorphisms and co-clones has received a lot of attention in regard to constraint satisfaction problems. However, it fails if we are interested in a reduction giving equivalence instead of only satisfiability-equivalence. We show how a similar Galois connection involving weaker closure operators can be applied for these problems. As an example of the usefulness of our construction, we show how to obtain very short proofs of complexity classifications in this context.

Cite as

Henning Schnoor and Ilka Schnoor. New Algebraic Tools for Constraint Satisfaction. In Complexity of Constraints. Dagstuhl Seminar Proceedings, Volume 6401, pp. 1-18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)


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@InProceedings{schnoor_et_al:DagSemProc.06401.7,
  author =	{Schnoor, Henning and Schnoor, Ilka},
  title =	{{New Algebraic Tools for Constraint Satisfaction}},
  booktitle =	{Complexity of Constraints},
  pages =	{1--18},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6401},
  editor =	{Nadia Creignou and Phokion Kolaitis and Heribert Vollmer},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06401.7},
  URN =		{urn:nbn:de:0030-drops-8057},
  doi =		{10.4230/DagSemProc.06401.7},
  annote =	{Keywords: Constraints, Partial Clones, Galois Correspondence}
}

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