English

Asymptotic structure. VI. Distant paths across a disc

Combinatorics 2025-09-10 v1

Abstract

Menger's theorem says that, for k0k\ge0, if S,TS, T are sets of vertices in a graph GG, then either there are k+1k + 1 vertex-disjoint paths between SS and TT, or there is a set X of at most kk vertices such that every SS-TT path passes through XX. The ``coarse Menger conjecture'' proposed a generalization of Menger's theorem for paths that are far apart: for all k,ck, c there exists \ell, such that for every graph GG and subsets S,TV(G)S, T \subset V (G), either there are k+1k + 1 paths between SS and TT, pairwise with distance more than cc, or there is a set XV(G)X \subset V (G) of at most kk vertices such that every SS-TT path has distance at most \ell from XX. This is known to be false, but may be true if GG is planar. Here we show that it is true if GG is planar and all vertices in STS \cup T are on the infinite region. In this case, we also obtain a linear-time algorithm to test for the existence of k+1k+ 1 paths between SS and TT, pairwise with distance more than cc.

Keywords

Cite

@article{arxiv.2509.07174,
  title  = {Asymptotic structure. VI. Distant paths across a disc},
  author = {Tung Nguyen and Alex Scott and Paul Seymour},
  journal= {arXiv preprint arXiv:2509.07174},
  year   = {2025}
}
R2 v1 2026-07-01T05:27:23.591Z