4 research outputs found
Approximating partition functions of bounded-degree Boolean counting Constraint Satisfaction Problems
We study the complexity of #CSPā(Γ), which is the problem of counting satisfying assignments to CSP instances with constraints from Γ and whose variables can appear at most ā times. Our main result shows that: (i) if every function in Γ is affine, then #CSPā(Γ) is in FP for all ā, (ii) otherwise, if every function in Γ is in a class called IM2, then for large ā, #CSPā(Γ) is equivalent under approximation-preserving reductions to the problem of counting independent sets in bipartite graphs, (iii) otherwise, for large ā, it is NP-hard to approximate #CSPā(Γ), even within an exponential factor.</p
Approximating partition functions of bounded-degree Boolean counting Constraint Satisfaction Problems
We study the complexity of #CSPā(Γ), which is the problem of counting satisfying assignments to CSP instances with constraints from Γ and whose variables can appear at most ā times. Our main result shows that: (i) if every function in Γ is affine, then #CSPā(Γ) is in FP for all ā, (ii) otherwise, if every function in Γ is in a class called IM2, then for large ā, #CSPā(Γ) is equivalent under approximation-preserving reductions to the problem of counting independent sets in bipartite graphs, (iii) otherwise, for large ā, it is NP-hard to approximate #CSPā(Γ), even within an exponential factor.</p
Approximating partition functions of bounded- degree Boolean counting Constraint Satisfaction Problems
We study the complexity of approximate counting Constraint Satisfaction Problems (#CSPs) in a bounded degree setting. Specifically, given a Boolean constraint language Ī and a degree bound Ī, we study the complexity of #CSPĪ(Ī), which is the problem of counting satisfying assignments to CSP instances with constraints from Ī and whose variables can appear at most Ī times. Our main result shows that: (i) if every function in Ī is affine, then #CSPĪ(Ī) is in FP for all Ī, (ii) otherwise, if every function in Ī is in a class called IM2, then for all sufficiently large Ī, #CSPĪ(Ī) is equivalent under approximation-preserving (AP) reductions to the counting problem #BIS (the problem of counting independent sets in bipartite graphs) (iii) otherwise, for all sufficiently large Ī, it is NP-hard to approximate the number of satisfying assignments of an instance of #CSPĪ(Ī), even within an exponential factor. Our result extends previous results, which apply only in the so-called āconservativeā case. A full version of the paper containing detailed proofs is available at http://arxiv.org/abs/1610.04055 and is attached as an appendix. Theorem-numbering here matches the full version