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On-line size Ramsey number for monotone k-uniform ordered paths with uniform looseness
European Journal of Combinatorics ( IF 1.0 ) Pub Date : 2020-09-24 , DOI: 10.1016/j.ejc.2020.103242
Xavier Pérez-Giménez , Paweł Prałat , Douglas B. West

An ordered hypergraph is a hypergraph H with a specified linear ordering of the vertices, and the appearance of an ordered hypergraph G in H must respect the specified order on V(G). In on-line Ramsey theory, Builder iteratively presents edges that Painter must immediately color. The t-color on-line size Ramsey number R̃t(G) of an ordered hypergraph G is the minimum number of edges Builder needs to play (on a large ordered set of vertices) to force Painter using t colors to produce a monochromatic copy of G. The monotone tight path Pr(k) is the ordered hypergraph with r vertices whose edges are all sets of k consecutive vertices.

We obtain good bounds on R̃t(Pr(k)). Letting m=rk+1 (the number of edges in Pr(k)), we prove mt1(3t)R̃t(Pr(2))tmt+1. For general k, a trivial upper bound is Rk, where R is the least number of vertices in a k-uniform (ordered) hypergraph whose t-colorings all contain Pr(k) (and is a tower of height k2). We prove R(klgR)R̃t(Pr(k))R(lgR)2+ε, where ε is a positive constant and tm is sufficiently large in terms of ε1. Our upper bounds improve prior results when t grows faster than mlogm. We also generalize our results to -loose monotone paths, where each successive edge begins vertices after the previous edge.



中文翻译:

单调的在线大小Ramsey数 ķ-具有均匀松散度的均匀有序路径

一个有序的超图是一个超图H 具有指定的顶点线性顺序和有序超图的外观 GH 必须遵守指定的命令 VG。在在线Ramsey理论中,Builder迭代地呈现Painter必须立即着色的边缘。的Ť色在线尺寸拉姆齐数 [R̃ŤG 有序超图 G 是Builder强制使用Painter使用(在大量有序的一组顶点上)播放的最小边数 Ť 颜色以产生的单色副本 G。该单调紧张的路径 P[Rķ 是有序超图 [R 顶点均为边集的顶点 ķ 连续的顶点。

我们在 [R̃ŤP[Rķ。出租=[R-ķ+1个 (中的边数 P[Rķ),我们证明 Ť-1个3Ť[R̃ŤP[R2ŤŤ+1个。对于一般ķ,一个很小的上限是 [Rķ,在哪里 [R 是一个顶点中最少数量的顶点 ķ-一致(有序)超图,其 Ť-所有颜色都包含 P[Rķ (并且是高塔 ķ-2)。我们证明[Rķlg[R[R̃ŤP[Rķ[Rlg[R2+ε,在哪里 ε 是一个正常数, Ť 就...而言足够大 ε-1个。在以下情况下,我们的上限可以改善先前的结果Ť 增长快于 日志。我们还将结果推广到-松散的单调路径,其中每个连续边开始 上一条边之后的顶点。

更新日期:2020-09-24
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