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arXiv 2102.01986math.CO
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关于带有多个阿贝尔群标记的图中循环的统一半整数埃罗什-波萨定理

A unified half-integral Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups

Institute for Basic Science (IBS)(基础科学研究院);National Institute of Informatics(信息学国立研究所);Incheon National University(仁川国立大学);KAIST(韩国科学技术院)

J. Pascal Gollin, Kevin Hendrey, Ken-ichi Kawarabayashi, O-joung Kwon, Sang-il Oum

AI总结:

本文提出一个关于带多个阿贝尔群标记的图中循环的统一半整数埃罗什-波萨定理,证明了在特定条件下循环包容量与击中所有循环的最小顶点集之间的对偶性。

摘要:

埃罗什和波萨于1965年证明了在图中,最大循环包容量与最小顶点集击中所有循环的最小大小之间存在对偶性。如果限制到奇数循环,则这种对偶性不成立。然而,1999年,雷德通过将打包放松为半整数打包证明了奇数循环的类似结果。我们证明了雷德定理的广泛推广:如果图的边被有限多个阿贝尔群标记,则存在一个对偶性,即半整数打包的最大大小与击中所有此类循环的最小顶点集大小之间存在对偶性。许多自然的循环属性可以在此设定中编码,例如长度至少为ℓ的循环、长度p模q的循环、与给定顶点集至少相交t次的循环,以及在图嵌入固定曲面时包含在给定的Z_2同调类中的循环。我们的主要结果使我们能够证明满足固定有限集的这些属性的循环的对偶定理。

英文摘要:

Erdős and Pósa proved in 1965 that there is a duality between the maximum size of a packing of cycles and the minimum size of a vertex set hitting all cycles. Such a duality does not hold if we restrict to odd cycles. However, in 1999, Reed proved an analogue for odd cycles by relaxing packing to half-integral packing. We prove a far-reaching generalisation of the theorem of Reed; if the edges of a graph are labelled by finitely many abelian groups, then there is a duality between the maximum size of a half-integral packing of cycles whose values avoid a fixed finite set for each abelian group and the minimum size of a vertex set hitting all such cycles. A multitude of natural properties of cycles can be encoded in this setting, for example cycles of length at least $\ell$, cycles of length $p$ modulo $q$, cycles intersecting a prescribed set of vertices at least $t$ times, and cycles contained in given $\mathbb{Z}_2$-homology classes in a graph embedded on a fixed surface. Our main result allows us to prove a duality theorem for cycles satisfying a fixed set of finitely many such properties.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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