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arXiv 1209.4971cs.DScs.CC
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检查优先级队列的流复杂度

Streaming Complexity of Checking Priority Queues

Nathanaël François, Frederic Magniez

摘要:

本文的工作是在设计有效的检查器来测试一些大规模数据结构的可靠性。给定对这样的结构的插入/提取操作的顺序存取,人们想要仅后验地决定它是否对应于可靠结构的演化。在大量数据的上下文中,人们希望最小化检查器的可靠内存量和操作序列上的传递次数。Chu、Kannan和McGregor发起了在这种情况下检查优先级队列的研究。他们表明,使用时间戳允许检查一个优先级队列与一个单一的通行证和内存空间O(N^(1/2)),直到一个多对数因子。后来,Chakrabarti,Cormode,Kondapally和McGregor删除了时间戳的使用,并证明了更多的通行证没有帮助。我们表明,即使在时间戳的存在下,更多的通行证没有帮助,解决了以前开放的问题。另一方面,我们证明了第二遍,但在相反的方向,将内存空间缩小到O((log N)^2),扩展了Magniez,Mathieu和Nayak第一次观察到的现象,用于检查带括号的表达式。

英文摘要:

This work is in the line of designing efficient checkers for testing the reliability of some massive data structures. Given a sequential access to the insert/extract operations on such a structure, one would like to decide, a posteriori only, if it corresponds to the evolution of a reliable structure. In a context of massive data, one would like to minimize both the amount of reliable memory of the checker and the number of passes on the sequence of operations. Chu, Kannan and McGregor initiated the study of checking priority queues in this setting. They showed that use of timestamps allows to check a priority queue with a single pass and memory space O(N^(1/2)), up to a polylogarithmic factor. Later, Chakrabarti, Cormode, Kondapally and McGregor removed the use of timestamps, and proved that more passes do not help. We show that, even in the presence of timestamps, more passes do not help, solving a previously open problem. On the other hand, we show that a second pass, but in reverse direction, shrinks the memory space to O((log N)^2), extending a phenomenon the first time observed by Magniez, Mathieu and Nayak for checking well-parenthesized expressions.

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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