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Article overview
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Schaefer's theorem for graphs | Manuel Bodirsky
; Michael Pinsker
; | Date: |
12 Nov 2010 | Abstract: | Schaefer’s theorem is a complexity classification result for so-called
Boolean constraint satisfaction problems: it states that every Boolean
constraint satisfaction problem is either contained in one out of six classes
and can be solved in polynomial time, or is NP-complete. We present an analog
of this dichotomy result for the first-order logic of graphs instead of Boolean
logic. In this generalization of Schaefer’s result, the input consists of a set
$W$ of variables and a conjunction $Phi$ of statements (’’constraints’’) about
these variables in the language of graphs, where each statement is taken from a
fixed finite set $Psi$ of allowed formulas; the question is whether $Phi$ is
satisfiable in a graph. We prove that either $Psi$ is contained in one out of
17 classes of graph formulas and the corresponding problem can be solved in
polynomial time, or the problem is NP-complete. This is achieved by a
universal-algebraic approach, which in turn allows us to use structural Ramsey
theory. To apply the universal-algebraic approach, we formulate the
computational problems under consideration as constraint satisfaction problems
(CSPs) whose templates are first-order definable in the countably infinite
random graph. Our method to then classify the computational complexity of those
CSPs produces many statements of independent mathematical interest. | Source: | arXiv, 1011.2894 | Services: | Forum | Review | PDF | Favorites |
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