We recover plane curves from their branch points under projection onto a line. Our focus lies on cubics and quartics. These have 6 and 12 branch points respectively. The plane Hurwitz numbers 40 and 120 count the orbits of solutions. We determine the numbers of real solutions, and we present exact algorithms for recovery. Our approach relies on 150 years of beautiful algebraic geometry, from Clebsch to Vakil and beyond.
翻译:我们通过将平面曲线投影到一条直线上从它们的分叉点中恢复出曲线。我们的焦点是三次和四次曲线。三次曲线有6个分叉点,四次曲线有12个。平面胡尔维茨数分别为40和120,可用来计算解的轨道。我们确定了实解的数量,并提出了恢复的确切算法。我们的方法依赖于美丽的代数几何,从克莱布施到瓦基尔及其后来者的150年历史。