论文标题

具有严格宽度的均匀图的一阶扩展的关系宽度

Relational Width of First-Order Expansions of Homogeneous Graphs with Bounded Strict Width

论文作者

Wrona, Michał

论文摘要

解决代数二分法的猜想,以解决与次数无限有限界均匀结构的一阶结构的约束满意度问题,这需要理解在这种情况下局部一致方法的适用性。我们研究了解决CSP的一致性量(通过关系宽度)的量,以求解CSP的一阶扩展s,这些图的一阶扩展s还具有严格宽度的限制,即为CSP的实例建立CSP实例的局部一致性,不仅可以确定每个解决方案是否有一个解决方案,还可以从back上获得一个back的实例,而不必分配一个差异。 Our main result is that the structures S under consideration have relational width exactly (2, L) where L is the maximal size of a forbidden subgraph of a homogeneous graph under consideration, but not smaller than 3. It beats the upper bound (2m, 3m) where m = max(arity(S)+1, L, 3) and arity(S) is the largest arity of a relation in S, which follows from a sufficient condition implying bounded文献的关系宽度。由于L可能是任意大的,因此我们的结果与有限结构的关系界限宽度层次结构的崩溃对比,其关系宽度(如果有限)最多总是是(2,3)。

Solving the algebraic dichotomy conjecture for constraint satisfaction problems over structures first-order definable in countably infinite finitely bounded homogeneous structures requires understanding the applicability of local-consistency methods in this setting. We study the amount of consistency (measured by relational width) needed to solve CSP for first-order expansions S of countably infinite homogeneous graphs that additionally have bounded strict width, i.e., for which establishing local consistency of an instance of the CSP not only decides if there is a solution but also ensures that every solution may be obtained from a locally consistent instance by greedily assigning values to variables, without backtracking. Our main result is that the structures S under consideration have relational width exactly (2, L) where L is the maximal size of a forbidden subgraph of a homogeneous graph under consideration, but not smaller than 3. It beats the upper bound (2m, 3m) where m = max(arity(S)+1, L, 3) and arity(S) is the largest arity of a relation in S, which follows from a sufficient condition implying bounded relational width from the literature. Since L may be arbitrarily large, our result contrasts the collapse of the relational bounded width hierarchy for finite structures , whose relational width, if finite, is always at most (2,3).

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源