论文标题
编译无连接性限制的无交叉几何图,以进行快速枚举,随机抽样和优化
Compiling Crossing-free Geometric Graphs with Connectivity Constraint for Fast Enumeration, Random Sampling, and Optimization
论文作者
论文摘要
给定平面中的$ n $点,我们提出算法将连接的无交叉几何图编译为有向的无环图(DAGS)。 DAG允许有效计数,枚举,随机抽样和优化。我们的算法依靠Wettstein的框架来编译几个无交叉的几何图。 Wettstein的显着贡献之一是允许处理具有连通性的几何图,因为众所周知,它很难有效地代表具有这种全局特性的几何图。为了实现这一目标,Wettstein提出了针对无跨越树木和无跨越跨越循环的专业技术,并发明了以$ \ mathrm {o}(7.044^n)$时间和$ \ mathrm {o}(5.619^n)$时间进行的编译算法。 我们的第一个贡献是提出一种更简单有效地处理连接约束的技术。它使算法的设计和分析变得更加容易,并且可以提高时间复杂性。我们的算法达到了$ \ mathrm {o}(6^n)$时间和$ \ mathrm {o}(4^n)$分别用于编译无交叉的跨越树和无交叉跨越周期的时间。作为第二个贡献,我们提出了一种算法,以优化由无交叉跨越周期所包围的区域。为了实现这一目标,我们修改了DAG,以便它具有其他信息。我们的算法以$ \ mathrm {o}(4.829^n)$时间运行,以找到给定点集的区域最小化(或最大化)的无交叉跨越周期。尽管该问题在2000年被证明是NP的完整算法,但据我们所知,没有比明显的$ \ Mathrm {O}(n!)$ TIME算法更快的算法。
Given $n$ points in the plane, we propose algorithms to compile connected crossing-free geometric graphs into directed acyclic graphs (DAGs). The DAGs allow efficient counting, enumeration, random sampling, and optimization. Our algorithms rely on Wettstein's framework to compile several crossing-free geometric graphs. One of the remarkable contributions of Wettstein is to allow dealing with geometric graphs with connectivity, since it is known to be difficult to efficiently represent geometric graphs with such global property. To achieve this, Wettstein proposed specialized techniques for crossing-free spanning trees and crossing-free spanning cycles and invented compiling algorithms running in $\mathrm{O}(7.044^n)$ time and $\mathrm{O}(5.619^n)$ time, respectively. Our first contribution is to propose a technique to deal with the connectivity constraint more simply and efficiently. It makes the design and analysis of algorithms easier, and yields improved time complexity. Our algorithms achieve $\mathrm{O}(6^n)$ time and $\mathrm{O}(4^n)$ time for compiling crossing-free spanning trees and crossing-free spanning cycles, respectively. As the second contribution, we propose an algorithm to optimize the area surrounded by crossing-free spanning cycles. To achieve this, we modify the DAG so that it has additional information. Our algorithm runs in $\mathrm{O}(4.829^n)$ time to find an area-minimized (or maximized) crossing-free spanning cycle of a given point set. Although the problem was shown to be NP-complete in 2000, as far as we know, there were no known algorithms faster than the obvious $\mathrm{O}(n!)$ time algorithm for 20 years.