Kelly's theorem states that a set of $n$ points affinely spanning $\mathbb{C}^3$ must determine at least one ordinary complex line (a line passing through exactly two of the points). Our main theorem shows that such sets determine at least $3n/2$ ordinary lines, unless the configuration has $n-1$ points in a plane and one point outside the plane (in which case there are at least $n-1$ ordinary lines). In addition, when at most $2n/3$ points are contained in any plane, we prove a theorem giving stronger bounds that take advantage of the existence of lines with 4 and more points (in the spirit of Melchior's and Hirzebruch's inequalities). Furthermore, when the points span 4 or more dimensions, with at most $2n/3$ points contained in any three dimensional affine subspace, we show that there must be a quadratic number of ordinary lines.
翻译:Kelly 的理论指出, 一组折成折叠的美元点必须确定至少一条普通的复杂线( 一条直通两点的线条 ) 。 我们的主要理论显示, 这样的线条至少确定 $2 美元 。 除非配置在平面上有 $1 美元点, 而在平面外也有一个点点( 在平面上至少有 $1 美元 普通线条 ) 。 此外, 当任何平面平面上最多包含 $2 / 3 美元点时, 我们证明一个理论提供了更强的界限, 利用4 个或 以上 点的线条线条( 本着Melchior 和 Hirzebruch 的不平等精神 ) 。 此外, 当这些点点跨过 4 或 个或 以上 维度时, 最多 $ $ $ $/3 点 在任何 3 维的平面平面亚空间中, 我们显示 必须有 普通线的四等数 。