Abstract
A graph is called \(2K_2\)-free if it does not contain two independent edges as an induced subgraph. Gao and Pasechnik conjectured that every \(\frac{3}{2}\)-tough \(2K_2\)-free graph with at least three vertices has a spanning trail with maximum degree at most 4. In this paper, we confirm this conjecture. We also provide examples for all \(t < \frac{5}{4}\) of t-tough graphs that do not have a spanning trail with maximum degree at most 4.
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Bauer, D., Broersma, H.J., Veldman, H.J.: Not every 2-tough graph is Hamiltonian. In: Proceedings of the 5th Twente Workshop on Graphs and Combinatorial Optimization (Enschede, 1997), vol. 99, pp. 317–321 (2000)
Bauer, D., Broersma, H.J., Schmeichel, E.: Toughness in graphs—a survey. Graphs Combin. 22(1), 1–35 (2006)
Broersma, H., Patel, V., Pyatkin, A.: On toughness and Hamiltonicity of \(2K_2\)-free graphs. J. Graph Theory 75(3), 244–255 (2014)
Chung, F.R.K., Gyárfás, A., Tuza, Z., Trotter, W.T.: The maximum number of edges in \(2K_2\)-free graphs of bounded degree. Discrete Math. 81(2), 129–135 (1990)
Chvátal, V.: Tough graphs and Hamiltonian circuits. Discrete Math. 5, 215–228 (1973)
El-Zahar, M., Erdős, P.: On the existence of two nonneighboring subgraphs in a graph. Combinatorica 5(4), 295–300 (1985)
Ellingham, M.N., Zha, X., Zhang, Y.: Spanning 2-trails from degree sum conditions. J. Graph Theory 45(4), 298–319 (2004)
Gao, M., Pasechnik, D.: On \(k\)-walks in \(2{K}_2\)-free graphs. (2014) arXiv:1412.0514v2
Gao, M., Pasechnik, D.: Edge-dominating cycles, \(k\)-walks and hamilton prisms in \(2{K}_2\)-free graphs. J. Knot Theory Ramif 25(12), 1642011.1–1642011.9 (2016)
Jackson, B ., Wormald, N .C.: \(k\)-walks of graphs. Australas. J. Combin 2, 135–146 (1990). Combinatorial mathematics and combinatorial computing, vol. 2 (Brisbane, 1989)
Li, Ping, Li, Hao, Chen, Ye, Fleischner, Herbert, Lai, Hong-Jian: Supereulerian graphs with width \(s\) and \(s\)-collapsible graphs. Discrete Appl. Math. 200, 79–94 (2016)
Meister, D.: Two characterisations of minimal triangulations of \(2K_2\)-free graphs. Discrete Math. 306(24), 3327–3333 (2006)
Paoli, M., Peck, G.W., Trotter Jr., W.T., West, D.B.: Large regular graphs with no induced \(2K_2\). Graphs Combin. 8(2), 165–197 (1992)
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M. N. Ellingham: Supported by Simons Foundation award 429625.
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Chen, G., Ellingham, M.N., Saito, A. et al. Spanning Trails with Maximum Degree at Most 4 in \(2K_2\)-Free Graphs. Graphs and Combinatorics 33, 1095–1101 (2017). https://doi.org/10.1007/s00373-017-1823-2
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DOI: https://doi.org/10.1007/s00373-017-1823-2