Journal of Combinatorial Theory Series B ( IF 1.2 ) Pub Date : 2022-05-16 , DOI: 10.1016/j.jctb.2022.04.007 Amarja Kathapurkar , Richard Montgomery
In 2001, Komlós, Sárközy and Szemerédi proved that, for each , there is some and such that, if , then every n-vertex graph with minimum degree at least contains a copy of every n-vertex tree with maximum degree at most . We prove the corresponding result for directed graphs. That is, for each , there is some and such that, if , then every n-vertex directed graph with minimum semi-degree at least contains a copy of every n-vertex oriented tree whose underlying maximum degree is at most .
As with Komlós, Sárközy and Szemerédi's theorem, this is tight up to the value of c. Our result improves a recent result of Mycroft and Naia, which requires the oriented trees to have underlying maximum degree at most Δ, for any constant and sufficiently large n. In contrast to these results, our methods do not use Szemerédi's regularity lemma.
中文翻译:
在密集有向图中生成树
2001 年,Komlós、Sárközy 和 Szemerédi 证明,对于每个, 有一些和这样,如果, 则至少每个度数最小的n顶点图包含最多具有最大度数的每个n顶点树的副本. 我们证明了有向图的相应结果。也就是说,对于每个, 有一些和这样,如果, 则每一个至少具有最小半度数的n顶点有向图包含每个面向n顶点的树的副本,其基础最大度数最多为.
与 Komlós、Sárközy 和 Szemerédi 定理一样,这与c的值紧密相关。我们的结果改进了 Mycroft 和 Naia 的最近结果,这要求定向树具有最多 Δ 的潜在最大度数,对于任何常数并且足够大的n。与这些结果相反,我们的方法不使用 Szemerédi 的正则引理。