Universal algebra and hardness results for constraint satisfaction problems
نویسندگان
چکیده
منابع مشابه
Universal Algebra and Hardness Results for Constraint Satisfaction Problems
We present algebraic conditions on constraint languages Γ that ensure the hardness of the constraint satisfaction problem CSP(Γ ) for complexity classes L, NL, P, NP and ModpL. These criteria also give non-expressibility results for various restrictions of Datalog. Furthermore, we show that if CSP(Γ ) is not first-order definable then it is L-hard. Our proofs rely on tame congruence theory and ...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2009
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2008.12.048