Journal of Combinatorial Theory Series B ( IF 1.2 ) Pub Date : 2020-08-24 , DOI: 10.1016/j.jctb.2020.08.003 Binlong Li , Bo Ning
For a 2-connected graph G on n vertices and two vertices , we prove that there is an -path of length at least k, if there are at least vertices in of degree at least k. This strengthens a celebrated theorem due to Erdős and Gallai in 1959. As the first application of this result, we show that a 2-connected graph with n vertices contains a cycle of length at least 2k, if it has at least vertices of degree at least k. This confirms a 1975 conjecture made by Woodall. As other applications, we obtain some results which generalize previous theorems of Dirac, Erdős-Gallai, Bondy, and Fujisawa et al., present short proofs of the path case of Loebl-Komlós-Sós Conjecture which was verified by Bazgan et al. and a conjecture of Bondy on longest cycles (for large graphs) which was confirmed by Fraisse and Fournier, and make progress on a conjecture of Bermond.
中文翻译:
Erdős-Gallai定理的加强和Woodall猜想的证明
对于2个连通图G的n个顶点和两个顶点,我们证明有一个 -长度至少为k的路径,如果至少存在 顶点 的度数至少为k。这加强了1959年由Erdős和Gallai提出的著名定理。作为该结果的首次应用,我们证明了2个具有n个顶点的连通图包含一个长度至少为2 k的循环,如果它具有至少一个顶点度至少为k。这证实了伍德奥尔(Woodall)在1975年提出的猜想。作为其他应用,我们获得了一些结果,这些结果推广了Dirac,Erdős-Gallai,Bondy和Fujisawa等人的先前定理,为Loebl-Komlós-Sós猜想的路径情形提供了简短证明,并得到了Bazgan等人的验证。Fraisse和Fournier证实了最长周期的邦迪猜想(对于大图),而伯蒙德的猜想也在不断发展。