English

Fractional factors and component factors in graphs with isolated toughness smaller than 1

Combinatorics 2024-09-24 v2

Abstract

Let GG be a simple graph and let n,mn,m be two integers with 0<m<n0<m<n. We prove that iso(GS)nmSiso(G-S)\leq \frac{n}{m}|S| for every SV(G)S \subset V(G) if and only if GG has a {C2i+1,T ⁣:1i<mnm,TTnm}\{C_{2i+1},T \colon 1 \leq i < \frac{m}{n-m}, T\in\mathcal{T}_{\frac{n}{m}}\}-factor, where iso(GS)iso(G-S) denotes the number of isolated vertices of GSG-S and Tnm\mathcal{T}_{\frac{n}{m}} is a special family of trees. Furthermore, we characterize the trees in Tnm\mathcal{T}_{\frac{n}{m}} in terms of their bipartition.

Keywords

Cite

@article{arxiv.2312.11095,
  title  = {Fractional factors and component factors in graphs with isolated toughness smaller than 1},
  author = {Isaak H. Wolf},
  journal= {arXiv preprint arXiv:2312.11095},
  year   = {2024}
}

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14 pages