English

On Fan's conjecture about $4$-flow

Combinatorics 2023-06-21 v2

Abstract

Let GG be a bridgeless graph, CC is a circuit of GG. Fan proposed a conjecture that if G/CG/C admits a nowhere-zero 4-flow, then GG admits a 4-flow (D,f)(D,f) such that E(G)E(C)E(G)-E(C)\subseteq supp(f)(f) and supp(f)E(C)>34E(C)|\textrm{supp}(f)\cap E(C)|>\frac{3}{4}|E(C)|. The purpose of this conjecture is to find shorter circuit cover in bridgeless graphs. Fan showed that the conjecture holds for E(C)19.|E(C)|\le19. Wang, Lu and Zhang showed that the conjecture holds for E(C)27|E(C)|\le 27. In this paper, we prove that the conjecture holds for E(C)35.|E(C)|\le 35.

Keywords

Cite

@article{arxiv.2306.01493,
  title  = {On Fan's conjecture about $4$-flow},
  author = {Deping Song and Shuang Li and Xiao Wang},
  journal= {arXiv preprint arXiv:2306.01493},
  year   = {2023}
}
R2 v1 2026-06-28T10:54:31.132Z