English

On ends of degree $\omega_1$

Logic 2024-11-11 v1 Combinatorics

Abstract

We prove that if T T is a semi-special tree that is not special, then there exists a graph G G , formed as an inflation of a sparse T T -graph, such that for any special tree S S , G G is not a subdivision of an inflation of an sparse S S -graph. Furthermore GG has an end of uncountable degree that has no ray graph. This result provides a consistent negative answer to a problem posed by Stefan Geschke et al. in 2023. Additionally, we introduce and explore a property that generalizes Halin's grid theorem, extending it to ends of degree 1 \aleph_1 , which was originally established for ends of countable degree.

Keywords

Cite

@article{arxiv.2411.05241,
  title  = {On ends of degree $\omega_1$},
  author = {Leandro Aurichi and Gabriel Fernandes and Paulo Magalhães Júnior},
  journal= {arXiv preprint arXiv:2411.05241},
  year   = {2024}
}