作者: Stanislav Zivny , Andrei A. Bulatov
DOI: 10.1145/3389390
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摘要: In this paper we study the complexity of counting Constraint Satisfaction Problems (CSPs) form #CSP($\mathcal{C}$,-), in which goal is, given a relational structure $\mathbf{A}$ from class $\mathcal{C}$ structures and an arbitrary $\mathbf{B}$, to find number homomorphisms $\mathbf{B}$. Flum Grohe showed that #CSP($\mathcal{C}$,-) is solvable polynomial time if has bounded treewidth [FOCS'02]. Building on work [JACM'07] decision CSPs, Dalmau Jonsson then that, recursively enumerable arity, assuming FPT $\neq$ #W[1], there are no other cases exactly (or even fixed-parameter time) [TCS'04]. We show W[1] (under randomised parametrised reductions) for satisfying certain general conditions, not approximately unbounded treewidth; fixed parameter tractable (and thus also fully polynomial) approximation scheme #CSP($\mathcal{C}$,-). particular, our condition generalises case when closed under taking minors.