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arXiv 1005.0418cs.DScs.CG
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基于度量展开的近邻搜索下界

Lower Bounds on Near Neighbor Search via Metric Expansion

Rina Panigrahy, Kunal Talwar, Udi Wieder

摘要:

在本文中,我们将展示如何执行最近邻(NNS)搜索度量空间的复杂性是有关的度量空间的扩展。给定一个度量空间,我们观察通过连接一定距离$r$内的每对点而得到的图。然后,我们看看各种概念的扩展在这个图中将它们与细胞探针的复杂性NNS随机和确定性,精确和近似算法。例如,如果图有节点扩展$Φ$,那么我们证明任何确定性$t$ -探测数据结构的$n$点必须使用空间$S$,其中$(St/n)^t > Φ$。我们也展示了随机算法的类似结果。这些关系可以用来导出大多数已知的下界在著名的度量空间,如$l_1$,$l_2$,$l_\infty$通过简单地计算它们的扩展。在这个过程中,我们加强和推广我们以前的结果(FOCS 2008)。此外,我们统一的方法,在这项工作和通信复杂性为基础的方法。我们的工作减少了证明细胞探测下界的近邻搜索计算适当的扩展参数的问题。在我们的结果中,和以前所有的结果一样,对$t$的依赖性很弱;也就是说,在$t$中,束缚指数下降。我们展示了一个更强大的(紧)的时间-空间权衡的动态低竞争的数据结构的类。这些数据结构支持数据集中的更新,并且不会过于频繁地查找任何单个单元格。

英文摘要:

In this paper we show how the complexity of performing nearest neighbor (NNS) search on a metric space is related to the expansion of the metric space. Given a metric space we look at the graph obtained by connecting every pair of points within a certain distance $r$ . We then look at various notions of expansion in this graph relating them to the cell probe complexity of NNS for randomized and deterministic, exact and approximate algorithms. For example if the graph has node expansion $Φ$ then we show that any deterministic $t$-probe data structure for $n$ points must use space $S$ where $(St/n)^t > Φ$. We show similar results for randomized algorithms as well. These relationships can be used to derive most of the known lower bounds in the well known metric spaces such as $l_1$, $l_2$, $l_\infty$ by simply computing their expansion. In the process, we strengthen and generalize our previous results (FOCS 2008). Additionally, we unify the approach in that work and the communication complexity based approach. Our work reduces the problem of proving cell probe lower bounds of near neighbor search to computing the appropriate expansion parameter. In our results, as in all previous results, the dependence on $t$ is weak; that is, the bound drops exponentially in $t$. We show a much stronger (tight) time-space tradeoff for the class of dynamic low contention data structures. These are data structures that supports updates in the data set and that do not look up any single cell too often.

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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