On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction

The universal-algebraic approach has proved a powerful tool in the study of the complexity of CSPs. This approach has previously been applied to the study of CSPs with finite or (infinite) omega-categorical templates, and relies on two facts. The first is that in finite or omega-categorical structur...

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Main Authors: Barnaby Martin, Manuel Bodirsky, Martin Hils
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2012-09-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/674/pdf
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author Barnaby Martin
Manuel Bodirsky
Martin Hils
author_facet Barnaby Martin
Manuel Bodirsky
Martin Hils
author_sort Barnaby Martin
collection DOAJ
description The universal-algebraic approach has proved a powerful tool in the study of the complexity of CSPs. This approach has previously been applied to the study of CSPs with finite or (infinite) omega-categorical templates, and relies on two facts. The first is that in finite or omega-categorical structures A, a relation is primitive positive definable if and only if it is preserved by the polymorphisms of A. The second is that every finite or omega-categorical structure is homomorphically equivalent to a core structure. In this paper, we present generalizations of these facts to infinite structures that are not necessarily omega-categorical. (This abstract has been severely curtailed by the space constraints of arXiv -- please read the full abstract in the article.) Finally, we present applications of our general results to the description and analysis of the complexity of CSPs. In particular, we give general hardness criteria based on the absence of polymorphisms that depend on more than one argument, and we present a polymorphism-based description of those CSPs that are first-order definable (and therefore can be solved in polynomial time).
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spelling doaj.art-025db35ff4d9422a921ec79672e4a2452024-03-08T09:28:00ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742012-09-01Volume 8, Issue 310.2168/LMCS-8(3:13)2012674On the Scope of the Universal-Algebraic Approach to Constraint SatisfactionBarnaby Martinhttps://orcid.org/0000-0002-4642-8614Manuel Bodirskyhttps://orcid.org/0000-0001-8228-3611Martin Hilshttps://orcid.org/0000-0002-4304-288XThe universal-algebraic approach has proved a powerful tool in the study of the complexity of CSPs. This approach has previously been applied to the study of CSPs with finite or (infinite) omega-categorical templates, and relies on two facts. The first is that in finite or omega-categorical structures A, a relation is primitive positive definable if and only if it is preserved by the polymorphisms of A. The second is that every finite or omega-categorical structure is homomorphically equivalent to a core structure. In this paper, we present generalizations of these facts to infinite structures that are not necessarily omega-categorical. (This abstract has been severely curtailed by the space constraints of arXiv -- please read the full abstract in the article.) Finally, we present applications of our general results to the description and analysis of the complexity of CSPs. In particular, we give general hardness criteria based on the absence of polymorphisms that depend on more than one argument, and we present a polymorphism-based description of those CSPs that are first-order definable (and therefore can be solved in polynomial time).https://lmcs.episciences.org/674/pdfcomputer science - logic in computer sciencecomputer science - artificial intelligencecomputer science - computational complexity
spellingShingle Barnaby Martin
Manuel Bodirsky
Martin Hils
On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
Logical Methods in Computer Science
computer science - logic in computer science
computer science - artificial intelligence
computer science - computational complexity
title On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
title_full On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
title_fullStr On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
title_full_unstemmed On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
title_short On the Scope of the Universal-Algebraic Approach to Constraint Satisfaction
title_sort on the scope of the universal algebraic approach to constraint satisfaction
topic computer science - logic in computer science
computer science - artificial intelligence
computer science - computational complexity
url https://lmcs.episciences.org/674/pdf
work_keys_str_mv AT barnabymartin onthescopeoftheuniversalalgebraicapproachtoconstraintsatisfaction
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AT martinhils onthescopeoftheuniversalalgebraicapproachtoconstraintsatisfaction