A quadratic lower bound for Topswops

被引:2
|
作者
Morales, Linda [1 ]
Sudborough, Hal [1 ]
机构
[1] Univ Texas Dallas, Dept Comp Sci, Erik Jonsson Sch Engn & Comp Sci, Richardson, TX 75083 USA
关键词
Topswops; Reverse card shuffle; Pancake problem; Prefix reversals; Lower bounds; Permutations; Conway card games;
D O I
10.1016/j.tcs.2010.08.011
中图分类号
TP301 [理论、方法];
学科分类号
081202 ;
摘要
A quadratic lower bound for the topswops function is exhibited. This provides a non-trivial lower bound for a problem posed by J.H. Conway, D.E. Knuth, M. Gardner and others. We describe an infinite family of permutations, each taking a linear number of steps for the topswops process to terminate, and a chaining process that creates from them an infinite family of permutations taking a quadratic number of steps to reach a fixed point with the identity permutation. (C) 2010 Elsevier B.V. All rights reserved.
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页码:3965 / 3970
页数:6
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