English

A note on the number of non-cycle components in a pseudo 2-factor of graphs

Combinatorics 2025-10-15 v1

Abstract

A pseudo 2-factor of a graph is a spanning subgraph such that each component is K1K_1, K2K_2, or a cycle. This notion was introduced by Bekkai and Kouider in 2009, where they showed that every graph GG has a pseudo 2-factor with at most α(G)δ(G)+1\alpha(G)-\delta(G)+1 components that are not cycles. For a graph GG and a set of vertices SS, let δG(S)\delta_G(S) denote the minimum degree of vertices in SS. In this note, we show that every graph GG has a pseudo 2-factor with at most f(G)f(G) components that are not cycles, where f(G)f(G) is the maximum value of IδG(I)+1|I|-\delta_G(I)+1 among all independent sets II of GG. This result is a common generalization of a result by Bekkai and Kouider and a previous result by the author on the existence of a 2-factor.

Keywords

Cite

@article{arxiv.2510.12155,
  title  = {A note on the number of non-cycle components in a pseudo 2-factor of graphs},
  author = {Masaki Kashima},
  journal= {arXiv preprint arXiv:2510.12155},
  year   = {2025}
}

Comments

7 pages