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CSR
2006
Springer

The Complexity of Equality Constraint Languages

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The Complexity of Equality Constraint Languages
We classify the computational complexity of all constraint satisfaction problems where the constraint language is preserved by all permutations of the domain. A constraint language is preserved by all permutations of the domain if and only if all the relations in the language can be defined by boolean combinations of the equality relation. We call the corresponding constraint languages equality constraint languages. For the classification result we apply the universal-algebraic approach to infinite-valued constraint satisfaction, and show that an equality constraint language is tractable if it admits a constant unary polymorphism or an injective binary polymorphism, and is NP-complete otherwise. We also discuss how to determine algorithmically whether a given constraint language is tractable.
Manuel Bodirsky, Jan Kára
Added 22 Aug 2010
Updated 22 Aug 2010
Type Conference
Year 2006
Where CSR
Authors Manuel Bodirsky, Jan Kára
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