English

Rooted $C_5$-Minors

Combinatorics 2025-11-03 v1

Abstract

Let GG be a graph and x1,x2,,xkx_1, x_2, \ldots, x_k be distinct vertices of GG. We say (G,x1x2xk)(G,x_1x_2\ldots x_k) has a CkC_k-minor or GG has a CkC_k-minor rooted at x1x2xkx_1x_2\ldots x_k, if there exist pairwise disjoint sets X1,X2,,XkV(G)X_1, X_2, \ldots, X_k\subseteq V(G), such that for all i[k]i\in [k], G[Xi]G[X_i] is connected, xiXix_i\in X_i, and GG has an edge between XiX_i and Xi+1X_{i+1}, where Xk+1=XkX_{k+1}=X_k. When k=3k=3 it is easy to determine when (G,x1x2x3)(G,x_1x_2x_3) contains a C3C_3-minor. For k=4k=4, Robertson, Seymour and Thomas gave a characterization of (G,x1x2x3x4)(G,x_1x_2x_3x_4) with no C4C_4-minor, which, in particular, implies that such GG has connectivity at most 5. In this paper, we apply a method of Thomas and Wollan to prove a result, which implies that if GG is 1010-connected then, for all distinct vertices x1,x2,x3,x4,x5x_1,x_2,x_3,x_4,x_5 of GG, (G,x1x2x3x4x5)(G,x_1x_2x_3x_4x_5) has a C5C_5-minor.

Cite

@article{arxiv.2510.27161,
  title  = {Rooted $C_5$-Minors},
  author = {Xiying Du and Yanjia Li and Xingxing Yu},
  journal= {arXiv preprint arXiv:2510.27161},
  year   = {2025}
}

Comments

14 pages

R2 v1 2026-07-01T07:15:04.579Z