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arXiv 1002.0562cs.DScs.CCcs.GT
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针对k个谎言的最小值和最大值

Minimum and maximum against k lies

Michael Hoffmann, Jiří Matoušek, Yoshio Okamoto, Philipp Zumstein

摘要:

Pohl在1972年的一个简洁的结果断言,[3 n/2]-2次比较是足够的,并且在最坏的情况下也是必要的,可以找到一个n元全序集的最小值和最大值。通过oracle访问该集合以进行成对比较。最近,这个问题已经在Renyi-Ulam说谎者游戏的背景下进行了研究,其中预言机可能会给出k个错误的答案。对于大的k,由于Aigner的上界表明(k+O(\sqrt{k}))n次比较就足够了。我们对此进行了改进,提供了一个算法,对于某个常数C,最多有(k+1+C)n+O(k^3)次比较。已知的下界为(k+1+c_k)n-D,其中c_0=0.5,c_1=23/32=0.71875,当k趋于无穷大时,c_k=Ω(2^{-5k/4})。

英文摘要:

A neat 1972 result of Pohl asserts that [3n/2]-2 comparisons are sufficient, and also necessary in the worst case, for finding both the minimum and the maximum of an n-element totally ordered set. The set is accessed via an oracle for pairwise comparisons. More recently, the problem has been studied in the context of the Renyi-Ulam liar games, where the oracle may give up to k false answers. For large k, an upper bound due to Aigner shows that (k+O(\sqrt{k}))n comparisons suffice. We improve on this by providing an algorithm with at most (k+1+C)n+O(k^3) comparisons for some constant C. The known lower bounds are of the form (k+1+c_k)n-D, for some constant D, where c_0=0.5, c_1=23/32=0.71875, and c_k=Ω(2^{-5k/4}) as k goes to infinity.

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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