论文标题

改进了随机匹配问题的近似算法

Improved Approximation Algorithms for Stochastic-Matching Problems

论文作者

Adamczyk, Marek, Brubach, Brian, Grandoni, Fabrizio, Sankararaman, Karthik A., Srinivasan, Aravind, Xu, Pan

论文摘要

我们考虑了随机匹配的问题,这是由肾脏交换和在线约会中的应用所激发的。在此问题中,我们为我们提供了一个无方向的图。每个边缘都被分配了已知的,独立的存在概率和正权重(或利润)。我们必须探测优势才能发现它是否存在。为每个节点分配一个正整数,称为超时(或耐心)。在此随机图上,我们正在执行一个过程,该过程逐一探测边缘并逐渐构建匹配。该过程以两种方式约束。首先,如果存在探测的边缘,则必须不可撤销地将其添加到匹配(查询信号模型)中。其次,节点$ v $上限的超时将事件的边缘数量到$ v $。目标是最大化构造匹配的预期重量。 对于这个问题,Bansal等人。 (Algorithmica 2012)提供了$ 0.33 $ - 二分图算法的算法和一般图表的$ 0.25 $ - APPRXIMATION。我们将近似因素分别提高到$ 0.39 $和0.269美元。 结果中的主要技术成分是一种新颖的方法,可以根据不均匀的随机排列探测边缘。用一种最适合大概率边缘(加上其他想法)来修补此方法的方法,从而改善了近似因素。

We consider the Stochastic Matching problem, which is motivated by applications in kidney exchange and online dating. In this problem, we are given an undirected graph. Each edge is assigned a known, independent probability of existence and a positive weight (or profit). We must probe an edge to discover whether or not it exists. Each node is assigned a positive integer called a timeout (or a patience). On this random graph we are executing a process, which probes the edges one-by-one and gradually constructs a matching. The process is constrained in two ways. First, if a probed edge exists, it must be added irrevocably to the matching (the query-commit model). Second, the timeout of a node $v$ upper-bounds the number of edges incident to $v$ that can be probed. The goal is to maximize the expected weight of the constructed matching. For this problem, Bansal et al. (Algorithmica 2012) provided a $0.33$-approximation algorithm for bipartite graphs and a $0.25$-approximation for general graphs. We improve the approximation factors to $0.39$ and $0.269$, respectively. The main technical ingredient in our result is a novel way of probing edges according to a not-uniformly-random permutation. Patching this method with an algorithm that works best for large-probability edges (plus additional ideas) leads to our improved approximation factors.

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