English

Hindrance from a wasteful partial linkage

Combinatorics 2025-06-10 v2

Abstract

Let D=(V,E) D=(V,E) be a (possibly infinite) digraph and A,BV A,B\subseteq V . A hindrance consists of an AB AB -separator S S together with a set of disjoint AS AS -paths linking a proper subset of A A onto S S . Hindrances and configurations guaranteeing the existence of hindrances play an essential role in the proof of the infinite version of Menger's theorem and are important in the context of certain open problems as well. This motivates the investigation of circumstances under which hindrances appear. In this paper we show that if there is a ``wasteful partial linkage'', i.e. a set P \mathcal{P} of disjoint AB AB -paths with fewer unused vertices in B B than in A A , then there exists a hindrance.

Cite

@article{arxiv.2410.19583,
  title  = {Hindrance from a wasteful partial linkage},
  author = {Attila Joó},
  journal= {arXiv preprint arXiv:2410.19583},
  year   = {2025}
}
R2 v1 2026-06-28T19:35:36.411Z