论文标题

当对称不够时:硬性约束满意度问题的层次结构

When symmetries are not enough: a hierarchy of hard Constraint Satisfaction Problems

论文作者

Gillibert, Pierre, Jonušas, Julius, Kompatscher, Michael, Mottet, Antoine, Pinsker, Michael

论文摘要

我们通过应用模型理论结构(对hrushosvki-oding的改进)来生产具有有限签名的$ω$分类结构,以$ω$ - 分类结构可能是无限签名的。我们表明,编码的结构保留原始结构的理想代数特性,但是与这些结构相关的约束满意度问题(CSP)可以在计算复杂性方面表现不佳。这种方法使我们能够系统地生成$ω$ - 分类模板,其CSP的CSP对于任意高复杂性的各种复杂性类别以及$ω$ - 分类模板的完整类别,这些模板表明,任何给定复杂性类别中的成员资格都不能由多态性的一组身份表达。此外,这使我们能够证明,关于拓扑对于$ω$ - 分类结构的多态性克隆的相关性的最新结果也适用于CSP模板,即有限语言的结构。最后,我们获得了一个具体的代数标准,该标准可以构成二分法猜想中的易术和NP - 硬度之间的描述,以构成有限界限均质结构的一阶还原。

We produce a class of $ω$-categorical structures with finite signature by applying a model-theoretic construction -- a refinement of the Hrushosvki-encoding -- to $ω$-categorical structures in a possibly infinite signature. We show that the encoded structures retain desirable algebraic properties of the original structures, but that the constraint satisfaction problems (CSPs) associated with these structures can be badly behaved in terms of computational complexity. This method allows us to systematically generate $ω$-categorical templates whose CSPs are complete for a variety of complexity classes of arbitrarily high complexity, and $ω$-categorical templates that show that membership in any given complexity class cannot be expressed by a set of identities on the polymorphisms. It moreover enables us to prove that recent results about the relevance of topology on polymorphism clones of $ω$-categorical structures also apply for CSP templates, i.e., structures in a finite language. Finally, we obtain a concrete algebraic criterion which could constitute a description of the delineation between tractability and NP-hardness in the dichotomy conjecture for first-order reducts of finitely bounded homogeneous structures.

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