arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2102.05548cs.DScs.DM
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突破拟阵交的二次障碍

Breaking the Quadratic Barrier for Matroid Intersection

Joakim Blikstad, Jan van den Brand, Sagnik Mukhopadhyay, Danupon Nanongkai

摘要:

拟阵求交问题是近半个世纪以来被广泛研究的一个基本问题。在这个问题的经典版本中,我们在$n$元素的注释基集合$V$上给出两个拟阵$\mathcal{M}_1 = (V, \mathcal{I}_1)$和$\mathcal{M}_2 = (V, \mathcal{I}_2)$,然后我们必须通过进行形式为“Is $S \in \mathcal{I}_1 \cap \mathcal{I}_2$?或“是$S \in \mathcal{I}_2$吗?“用于$S \subseteq V$。目标是最小化查询的数量。击败现有的$\tilde O(n^2)$界限,被称为二次障碍,是一个开放的问题,从两个工作线捕捉技术的限制。第一个是经典的Cunningham算法[SICOMP 1986],其$\tilde O(n^2)$ -查询实现由CLS+ [FOCS 2019]和Nguyen [2019]展示。另一种是Lee,Sidford和Wong的一般切割平面方法[FOCS 2015]。打破二次障碍的唯一进展需要近似算法或更强大的排名Oracle查询[CLS+ FOCS 2019]。没有确切的算法与$o(n^2)$独立查询是已知的。在这项工作中,我们打破了二次障碍的随机算法保证$\tilde O(n^{9/5})$独立查询的概率很高,和一个确定性算法保证$\tilde O(n^{11/6})$独立查询。我们的主要见解是简单而快速的算法来解决标准扩充路径框架[Edmonds 1968]中出现的图可达性问题。结合这与以前的精确和近似算法导致我们的结果。

英文摘要:

The matroid intersection problem is a fundamental problem that has been extensively studied for half a century. In the classic version of this problem, we are given two matroids $\mathcal{M}_1 = (V, \mathcal{I}_1)$ and $\mathcal{M}_2 = (V, \mathcal{I}_2)$ on a comment ground set $V$ of $n$ elements, and then we have to find the largest common independent set $S \in \mathcal{I}_1 \cap \mathcal{I}_2$ by making independence oracle queries of the form "Is $S \in \mathcal{I}_1$?" or "Is $S \in \mathcal{I}_2$?" for $S \subseteq V$. The goal is to minimize the number of queries. Beating the existing $\tilde O(n^2)$ bound, known as the quadratic barrier, is an open problem that captures the limits of techniques from two lines of work. The first one is the classic Cunningham's algorithm [SICOMP 1986], whose $\tilde O(n^2)$-query implementations were shown by CLS+ [FOCS 2019] and Nguyen [2019]. The other one is the general cutting plane method of Lee, Sidford, and Wong [FOCS 2015]. The only progress towards breaking the quadratic barrier requires either approximation algorithms or a more powerful rank oracle query [CLS+ FOCS 2019]. No exact algorithm with $o(n^2)$ independence queries was known. In this work, we break the quadratic barrier with a randomized algorithm guaranteeing $\tilde O(n^{9/5})$ independence queries with high probability, and a deterministic algorithm guaranteeing $\tilde O(n^{11/6})$ independence queries. Our key insight is simple and fast algorithms to solve a graph reachability problem that arose in the standard augmenting path framework [Edmonds 1968]. Combining this with previous exact and approximation algorithms leads to our results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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