European Journal of Combinatorics ( IF 1.0 ) Pub Date : 2021-02-27 , DOI: 10.1016/j.ejc.2021.103321 Gábor Damásdi , Balázs Keszegh , David Malec , Casey Tompkins , Zhiyu Wang , Oscar Zamora
In 1964, Erdős, Hajnal and Moon introduced a saturation version of Turán’s classical theorem in extremal graph theory. In particular, they determined the minimum number of edges in a -free, -vertex graph with the property that the addition of any further edge yields a copy of . We consider analogues of this problem in other settings. We prove a saturation version of the Erdős–Szekeres theorem about monotone subsequences and saturation versions of some Ramsey-type theorems on graphs and Dilworth-type theorems on posets.
We also consider semisaturation problems, wherein we allow the family to have the forbidden configuration, but insist that any addition to the family yields a new copy of the forbidden configuration. In this setting, we prove a semisaturation version of the Erdős–Szekeres theorem on convex -gons, as well as multiple semisaturation theorems for sequences and posets.
中文翻译:
图,姿态和点集的拉姆西理论中的饱和问题
1964年,Erdős,Hajnal和Moon引入了图兰经典定理在极值图论中的饱和版本。特别是,他们确定了-自由, -vertex图,具有以下特性:添加任何其他边会产生以下内容的副本: 。我们在其他环境中考虑此问题的类似物。我们证明了关于单调子序列的Erdős-Szekeres定理的饱和版本,以及图上的某些Ramsey型定理和姿势集上的Dilworth型定理的饱和版本。
我们还考虑了半饱和问题,其中我们允许该族具有禁止的配置,但坚持认为,对该族的任何添加都会产生该禁止配置的新副本。在这种情况下,我们证明了凸上的Erdős-Szekeres定理的半饱和版本-gons以及序列和位姿的多个半饱和定理。