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A proof of the tree alternative conjecture under the topological minor relation
Journal of Combinatorial Theory Series B ( IF 1.4 ) Pub Date : 2023-08-29 , DOI: 10.1016/j.jctb.2023.08.001
Jorge Bruno , Paul J. Szeptycki

In 2006 Bonato and Tardif posed the Tree Alternative Conjecture (TAC): the equivalence class of a tree under the embeddability relation is, up to isomorphism, either trivial or infinite. In 2022 Abdi, et al. provided a rigorous exposition of a counter-example to TAC developed by Tetano in his 2008 PhD thesis. In this paper we provide a positive answer to TAC for a weaker type of graph relation: the topological minor relation. More precisely, letting [T] denote the equivalence class of T under the topological minor relation we show that

  • 1.

    |[T]|=1 or |[T]|0 and

  • 2.

    rV(T), |[(T,r)]|=1 or |[(T,r)]|0.

In particular, by means of curtailing trees, we show that for any tree T with at least one ray with infinitely many vertices with degree at least 3: |[T]|20.



中文翻译:

拓扑次关系下树替代猜想的证明

2006年,Bonato和Tardif提出了树替代猜想(TAC):在可嵌入性关系下,树的等价类在同构之前要么是平凡的,要么是无限的。2022 年,Abdi 等人。对 Tetano 在 2008 年博士论文中开发的 TAC 的反例进行了严格的阐述。在本文中,我们为较弱类型的图关系(拓扑次关系)提供了 TAC 的肯定答案。更准确地说,让[时间]表示拓扑次关系下T的等价类,我们证明

  • 1.

    |[时间]|=1或者|[时间]|0

  • 2.

    rεV时间,|[时间,r]|=1或者|[时间,r]|0

特别是,通过缩减树,我们证明对于任何具有至少一条射线且具有无限多个顶点且度数至少为 3 的树T :|[时间]|20

更新日期:2023-08-29
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