论文标题

完美的改组,较少的懒惰换位

Perfect shuffling with fewer lazy transpositions

论文作者

Groenland, Carla, Johnston, Tom, Radcliffe, Jamie, Scott, Alex

论文摘要

懒惰的换位$(a,b,p)$是随机排列,其标识与概率$ 1-p $和s_n $中的thresposition $ 1-p $(a,b)\ in s_n $具有概率$ p $。如果它们的组成分布均匀分布,则必须将一系列独立的懒惰换位序列?众所周知,有长度$ \ binom {n} 2 $的序列,但是序列较短吗?这是由Fitzsimons在2011年提出的,并在2018年由Angel和Holroyd独立。我们通过构建长度$ \ frac23 \ binom {n} 2+o(n \ log n \ log n)$来负面回答这个问题,并考虑一些相关问题。

A lazy transposition $(a,b,p)$ is the random permutation that equals the identity with probability $1-p$ and the transposition $(a,b)\in S_n$ with probability $p$. How long must a sequence of independent lazy transpositions be if their composition is uniformly distributed? It is known that there are sequences of length $\binom{n}2$, but are there shorter sequences? This was raised by Fitzsimons in 2011, and independently by Angel and Holroyd in 2018. We answer this question negatively by giving a construction of length $\frac23 \binom{n}2+O(n\log n)$, and consider some related questions.

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