Schaefer proved in 1978 that the Boolean constraint satisfaction problem for a given constraint language is either in P or is NP-complete, and identified all tractable cases. Schaefer's dichotomy theorem actually shows that there are at most two constraint satisfaction problems, up to polynomial-time isomorphism (and these isomorphism types are distinct if and only if P ≠ NP). We show that if one considers AC0 isomorphisms, then there are exactly six isomorphism types (assuming that the complexity classes NP, P, ⊕L, NL, and L are all distinct). © Springer-Verlag Berlin Heidelberg 2005.
CITATION STYLE
Allender, E., Bauland, M., Immerman, N., Schnoor, H., & Vollmer, H. (2005). The complexity of satisfiability problems: Refining Schaefer’s theorem. In Lecture Notes in Computer Science (Vol. 3618, pp. 71–82). Springer Verlag. https://doi.org/10.1007/11549345_8
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