论文标题

ω类别结构避免高度1个身份

ω-categorical structures avoiding height 1 identities

论文作者

Bodirsky, Manuel, Mottet, Antoine, Olšák, Miroslav, Opršal, Jakub, Pinsker, Michael, Willard, Ross

论文摘要

(无限)有限限制的同质结构还原的约束满意度问题(CSP)的代数二分法指出,如果模型的模型完全核心具有伪sigggggers聚合物态度,则该CSP是多项式时间可及其。 与二分法有关的重要问题之一是,是否与有限结构相似,具有伪siggers多态性的条件可以通过满足固定身份1的固定身份的条件来代替多态性,即不包含功能符号的任何巢穴的身份。我们通过为每个非平凡的高度身份构建一个构建一个结构在猜想范围内,其多态性不满足这些身份,但其CSP仍然可以拖延,我们为这个问题提供了负面答案。 二分法猜想的同等表述是通过结构的多态性对非平凡高度1身份的局部满意度来表征CSP的障碍性。我们表明,非平凡高度1个身份的局部满意度和全球满意度因$ω$ - 分类结构而有所不同,其指数轨道增长不足,从而解决了此类结构的代数理论中的主要开放问题之一。

The algebraic dichotomy conjecture for Constraint Satisfaction Problems (CSPs) of reducts of (infinite) finitely bounded homogeneous structures states that such CSPs are polynomial-time tractable if the model-complete core of the template has a pseudo-Siggers polymorphism, and NP-complete otherwise. One of the important questions related to the dichotomy conjecture is whether, similarly to the case of finite structures, the condition of having a pseudo-Siggers polymorphism can be replaced by the condition of having polymorphisms satisfying a fixed set of identities of height 1, i.e., identities which do not contain any nesting of functional symbols. We provide a negative answer to this question by constructing for each non-trivial set of height 1 identities a structure within the range of the conjecture whose polymorphisms do not satisfy these identities, but whose CSP is tractable nevertheless. An equivalent formulation of the dichotomy conjecture characterizes tractability of the CSP via the local satisfaction of non-trivial height 1 identities by polymorphisms of the structure. We show that local satisfaction and global satisfaction of non-trivial height 1 identities differ for $ω$-categorical structures with less than doubly exponential orbit growth, thereby resolving one of the main open problems in the algebraic theory of such structures.

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