完全图半对壳可绘制的交叉数
摘要
Harary-Hill猜想指出,对于,的每次绘制至少有\begin{align*} H(n) := \frac{1}{4}\Big\lfloor\frac{n}{2}\Big\rfloor\Big\lfloor\frac{n-1}{2}\Big\rfloor\Big\lfloor\frac{n-2}{2}\Big\rfloor\Big\lfloor\frac{n-3}{2}\Big\rfloor \end{align*}个交叉。一般而言该问题仍未解决,但在受限绘制类上已有一些成功证明。这些类中最近期且最一般的是序列壳可绘制性。本工作中,我们改进了这些结果并引入半对壳可绘制这一新类。我们利用关于-边的全新结果证明了该新类的Harary-Hill猜想。迄今为止,针对特定类证明Harary-Hill猜想的方法依赖于固定的参考面。我们成功应用新技术以放宽此限制,从而在考虑子绘制时可选择不同参考面。此外,我们引入-偏差的概念,即最优-边数与实际-边数之差。借助-偏差,我们深入理解了-边的本质,并进一步降低了对固定参考面的必要性。
引用
@article{arxiv.1805.06780,
title = {The Crossing Number of Semi-Pair-Shellable Drawings of Complete Graphs},
author = {Petra Mutzel and Lutz Oettershagen},
journal= {arXiv preprint arXiv:1805.06780},
year = {2018}
}
备注
arXiv admin note: substantial text overlap with arXiv:1803.07515 Changes in updated version: - Title was changed: The reason is that the new class of drawings is not a superset of seq-shellable drawings and is only defined for odd n. Therefore the new name is a better fit. - Minor corrections of typos and language - Clearer introduction