Timeline for Why does the overhand shuffle converge to the uniform distribution on $S_n$?
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6 events
when toggle format | what | by | license | comment | |
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May 16, 2016 at 22:14 | vote | accept | Jack M | ||
May 16, 2016 at 22:13 | comment | added | Jack M | Thanks, I see now. Since I'm unfamiliar with this area I seriously overthought it. The uniform distribution is stationary because if $S$ is the shuffle and $X$ is the uniformly distributed prior state of the deck, then $$P(SX = \pi)=\sum_{\sigma\in S_n}P(X=\sigma)P(SX=\pi\sigma^{-1})=\frac1{n!}\sum_{\sigma\in S_n}P(SX=\pi\sigma^{-1})=\frac1{n!}$$ | |
May 16, 2016 at 18:10 | comment | added | Ori Gurel-Gurevich | @Jack M: There is a positive probability to apply to identity permutation, thus it is aperiodic. There is also a positive probability to transpose any two adjacent cards. It is easy to see that you can generate any permutation by transposing adjacent cards, thus it is irreducible. | |
May 16, 2016 at 13:16 | comment | added | Jack M | @OriGurel-Gurevich I've already read the proofs that for any irreducible and aperiodic Markov chain there is such a value of $t$, but I have to say it's not clear to me why this particular chain should be irreducible and aperiodic. | |
May 16, 2016 at 12:18 | comment | added | Ori Gurel-Gurevich | This is standard. All you need to prove is that the chain is irreducible and aperiodic. See, e.g., Proposition 1.7 in Levin, Peres and Wilmer's book here: pages.uoregon.edu/dlevin/MARKOV . | |
May 16, 2016 at 12:02 | history | answered | Douglas Zare | CC BY-SA 3.0 |