The toughness condition for connected {2,4}-factors

Let GG be a graph of order at least three, and write ω(GS)\omega(G\setminus S) for the number of components of GSG\setminus S. A connected 2,4\\{2,4\\}-factor is a connected spanning subgraph whose vertex degrees all belong to 2,4\\{2,4\\}. The connected 2,4\\{2,4\\}-factor conjecture. If

ω(GS)12S+1\omega(G\setminus S)\leq \frac{1}{2}|S|+1

for every SV(G)S\subseteq V(G), then GG admits a connected 2,4\\{2,4\\}-factor. The source states that this would simplify the preceding theorem, notes that it is true for strongly 22-tough graphs, and gives a restricted case in which it can be confirmed.

Sources & referencesView supporting material

Primary source

Morteza Hasanvand, “Spanning tree-connected subgraphs with small degrees”, arXiv:2205.05044 (2024).

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