English

A structure theorem for rooted connectivity in bidirected graphs

Combinatorics 2025-12-16 v2

Abstract

Recently, bidirected graphs have received increasing attention from the graph theory community with both structural and algorithmic results. Bidirected graphs are a generalization of directed graphs, consisting of an undirected graph together with a map assigning each endpoint of every edge either sign ++ or -. The connectivity properties of bidirected graphs are more complex than those of directed graphs and not yet well understood. In this paper, we show a structure theorem about rooted connectivity in bidirected graphs in terms of directed graphs. As applications, we prove Lov\'asz' flame theorem, Pym's theorem and a strong variant of Menger's theorem for a class of bidirected graphs and provide counterexamples in the general case.

Keywords

Cite

@article{arxiv.2509.23394,
  title  = {A structure theorem for rooted connectivity in bidirected graphs},
  author = {Tara Abrishami and Nathan Bowler and Attila Joó and Florian Reich and Qiuzhenyu Tao},
  journal= {arXiv preprint arXiv:2509.23394},
  year   = {2025}
}
R2 v1 2026-07-01T06:01:08.155Z