The Erd\H{o}s distinct distance problem is a ubiquitous problem in discrete geometry. Somewhat less well known is Erd\H{o}s' distinct angle problem, the problem of finding the minimum number of distinct angles between $n$ non-collinear points in the plane. Recent work has introduced bounds on a wide array of variants of this problem, inspired by similar variants in the distance setting. In this short note, we improve the best known upper bound for the minimum number of distinct angles formed by $n$ points in general position from $O(n^{\log_2(7)})$ to $O(n^2)$. Before this work, similar bounds relied on projections onto a generic plane from higher dimensional space. In this paper, we employ the geometric properties of a logarithmic spiral, sidestepping the need for a projection. We also apply this configuration to reduce the upper bound on the largest integer such that any set of $n$ points in general position has a subset of that size with all distinct angles. This bound is decreased from $O(n^{\log_2(7)/3})$ to $O(n^{1/2})$.
翻译:Erd\H{o} 不同的距离问题是离散几何中一个普遍存在的问题。 不太广为人知的是, Erd\H{o} 的独特角度问题, 即如何在平面上找到美元非双线点之间最小不同角度的问题。 最近的工作在距离设置中类似变量的启发下, 引入了这一问题各种变量的界限 。 在此简短的注释中, 我们改进了已知的最知名的上限, 即由美元( log_ 2(7)}) 至美元( nü2/2) 等方位形成的不同角度的最小数量。 在这项工作之前, 类似的界限依赖于从更高维度空间对通用平面的预测。 在本文中, 我们使用对数螺旋的几何特性, 并阻隔着对投影的需求。 我们还应用此配置来减少最大整数的上限, 因为任何总位置的 $( $_ log_ (7)} 的点都有一个不同角度的子 。 这个范围从 $O_\\\\\\\\\\\\ 3} 。