关于三连通平面图的平面贪婪图的面积要求
On the Area Requirements of Planar Greedy Drawings of Triconnected Planar Graphs
摘要:
本文研究了三连通平面图的平面贪婪图的面积要求。Cao,Strelzoff和Sun展示了三连通平面图的细分族$\cal H$,并声称在$\mathcal H$中的每一个平面图的贪婪绘制都需要指数面积。然而,我们发现,每一个$n$ -顶点图中的$\cal H$实际上有一个平面贪婪图纸尊重规定的平面嵌入在$O(n)\times O(n)$网格。这重新打开的问题是否三连通平面图承认平面贪婪图纸上的多项式大小的网格。此外,我们提供了一个肯定的答案,证明了每个$n$ -顶点Halin图承认一个平面的贪婪绘制上的$O(n)\times O(n)$网格上的上述问题的证据。这两个结果都是通过实际构造凸的和角单调的图来获得的。最后,我们考虑$α$ -施奈德图纸,这是角度单调,因此贪婪,如果$α\leq 30^\circ$,并表明存在平面三角形,每个$α$ -施奈德图纸与固定的$α<60^\circ$需要指数面积的任何决议规则。
英文摘要:
In this paper we study the area requirements of planar greedy drawings of triconnected planar graphs. Cao, Strelzoff, and Sun exhibited a family $\cal H$ of subdivisions of triconnected plane graphs and claimed that every planar greedy drawing of the graphs in $\mathcal H$ respecting the prescribed plane embedding requires exponential area. However, we show that every $n$-vertex graph in $\cal H$ actually has a planar greedy drawing respecting the prescribed plane embedding on an $O(n)\times O(n)$ grid. This reopens the question whether triconnected planar graphs admit planar greedy drawings on a polynomial-size grid. Further, we provide evidence for a positive answer to the above question by proving that every $n$-vertex Halin graph admits a planar greedy drawing on an $O(n)\times O(n)$ grid. Both such results are obtained by actually constructing drawings that are convex and angle-monotone. Finally, we consider $α$-Schnyder drawings, which are angle-monotone and hence greedy if $α\leq 30^\circ$, and show that there exist planar triangulations for which every $α$-Schnyder drawing with a fixed $α<60^\circ$ requires exponential area for any resolution rule.
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