Enumerating homomorphisms

Bulatov, AA and Dalmau, V and Grohe, M and Marx, Dániel (2012) Enumerating homomorphisms. JOURNAL OF COMPUTER AND SYSTEM SCIENCES, 78 (2). pp. 638-650. ISSN 0022-0000 10.1016/j.jcss.2011.09.006

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The homomorphism problem for relational structures is an abstract way of formulating constraint satisfaction problems (CSP) and various problems in database theory. The decision version of the homomorphism problem received a lot of attention in literature; in particular, the way the graph-theoretical structure of the variables and constraints influences the complexity of the problem is intensively studied. Here we study the problem of enumerating all the solutions with polynomial delay from a similar point of view. It turns out that the enumeration problem behaves very differently from the decision version. We give evidence that it is unlikely that a characterization result similar to the decision version can be obtained. Nevertheless, we show nontrivial cases where enumeration can be done with polynomial delay. © 2011 Elsevier Inc. All Rights Reserved.

Item Type: ISI Article
Uncontrolled Keywords: Constraint theory, Polynomials, Graph theory, Relational structures, Decision version, Data base theory, Constraint Satisfaction Problems, HOMOMORPHISMS, ENUMERATION, Constraint satisfaction, Computational complexity
Subjects: Q Science > QA Mathematics and Computer Science > QA75 Electronic computers. Computer science / számítástechnika, számítógéptudomány
Depositing User: EPrints Admin
Date Deposited: 16 Jan 2014 10:29
Last Modified: 05 Feb 2014 12:27
URI: https://eprints.sztaki.hu/id/eprint/7323

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