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arXiv 0905.3380math.CO
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双色点集中的平衡线

Balanced lines in two-coloured point sets

David Orden, Pedro Ramos, Gelasio Salazar

摘要:

令$B$和$R$是平面中的点集(分别是{ \em blue}和{ \em red}点的点集),使得$P:=B\cup R$处于一般位置,并且$|P|$是偶数。一条线$\ell$是{ \em平衡}的,如果它跨越一个蓝色点和一个红色点,并且在$\ell$的每个开放半平面上,蓝色点的数量减去红色点的数量是相同的。证明了$P$至少有$\min \{|B|,|R|\} $平衡线.这改进了Pach和Pinchasi的一个结果,他们在$|B|=|R|$的例子中证明了这一点。

英文摘要:

Let $B$ and $R$ be point sets (of {\em blue} and {\em red} points, respectively) in the plane, such that $P:=B\cup R$ is in general position, and $|P|$ is even. A line $\ell$ is {\em balanced} if it spans one blue and one red point, and on each open halfplane of $\ell$, the number of blue points minus the number of red points is the same. We prove that $P$ has at least $\min \{|B|,|R|\} $ balanced lines. This refines a result by Pach and Pinchasi, who proved this for the case $|B|=|R|$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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