Three polynomials are defined for given sets $S$ of $n$ points in general position in the plane: The Voronoi polynomial with coefficients the numbers of vertices of the order-$k$ Voronoi diagrams of~$S$, the circle polynomial with coefficients the numbers of circles through three points of $S$ enclosing $k$ points of $S$, and the $E_{\leq k}$ polynomial with coefficients the numbers of (at most $k$)-edges of~$S$. We present several formulas for the rectilinear crossing number of $S$ in terms of these polynomials and their roots. We also prove that the roots of the Voronoi polynomial lie on the unit circle if, and only if, $S$ is in convex position. Further, we present bounds on the location of the roots of these polynomials.
翻译:对于处于一般位置的平面点集 $S$(含 $n$ 个点),我们定义了三个多项式:Voronoi 多项式(其系数为 $S$ 的 $k$ 阶 Voronoi 图的顶点数)、圆多项式(其系数为通过 $S$ 中三个点且包含 $S$ 中 $k$ 个点的圆的数量),以及 $E_{\leq k}$ 多项式(其系数为 $S$ 中(至多 $k$ 条)边的数量)。我们给出了若干公式,利用这些多项式及其根来表示 $S$ 的直线交叉数。我们还证明了:Voronoi 多项式的根位于单位圆上当且仅当 $S$ 处于凸位置。此外,我们给出了这些多项式根的位置的界。