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 with a specified linear ordering of the vertices, and the appearance of an ordered hypergraph in must respect the specified order on . In on-line Ramsey theory, Builder iteratively presents edges that Painter must immediately color. The -color on-line size Ramsey number of an ordered hypergraph is the minimum number of edges Builder needs to play (on a large ordered set of vertices) to force Painter using colors to produce a monochromatic copy of . The monotone tight path is the ordered hypergraph with vertices whose edges are all sets of consecutive vertices.
We obtain good bounds on . Letting (the number of edges in ), we prove . For general , a trivial upper bound is , where is the least number of vertices in a -uniform (ordered) hypergraph whose -colorings all contain (and is a tower of height ). We prove , where is a positive constant and is sufficiently large in terms of . Our upper bounds improve prior results when grows faster than . 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 -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 具有指定的顶点线性顺序和有序超图的外观 在 必须遵守指定的命令 。在在线Ramsey理论中,Builder迭代地呈现Painter必须立即着色的边缘。的色在线尺寸拉姆齐数 有序超图 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 颜色以产生的单色副本 。该单调紧张的路径 是有序超图 顶点均为边集的顶点 连续的顶点。
我们在 。出租 (中的边数 ),我们证明 。对于一般,一个很小的上限是 ,在哪里 是一个顶点中最少数量的顶点 -一致(有序)超图,其 -所有颜色都包含 (并且是高塔 )。我们证明,在哪里 是一个正常数, 就...而言足够大 。在以下情况下,我们的上限可以改善先前的结果 增长快于 。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。