English

Tangles are Decided by Weighted Vertex Sets

Combinatorics 2025-05-16 v4

Abstract

We show that, given a k k -tangle τ \tau in a graph G G , there always exists a weight function w ⁣:V(G)N w\colon V(G)\to\mathbb{N} such that a separation (A,B) (A,B) of G G of order <k {<}k lies in τ \tau if and only if w(A)<w(B) w(A)<w(B) , where w(U):=uUw(u) w(U) := \sum_{u\in U}w(u) for UV(G) U\subseteq V(G) . We show that the same result holds also for tangles of hypergraphs as well as for edge-tangles of graphs, but not for edge-tangles of hypergraphs.

Keywords

Cite

@article{arxiv.1811.06821,
  title  = {Tangles are Decided by Weighted Vertex Sets},
  author = {Christian Elbracht and Jay Lilian Kneip and Maximilian Teegen},
  journal= {arXiv preprint arXiv:1811.06821},
  year   = {2025}
}

Comments

9 pages. Journal version, includes new section on edge tangles

R2 v1 2026-06-23T05:18:09.766Z