Questions tagged [pattern-avoidance]

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Pattern Avoidance in Poset Permutations

I am not sure if it is appropriate to use MathOverflow to publicize a conjecture, but I think this is an interesting question and I have no real ideas of how to solve it. A permutation on a $n$-...
Sam Hopkins's user avatar
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9 votes
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321-avoiding and parity-alternating permutations

It is classical that 321-avoiding permutations are enumerated by the Catalan numbers. A permutation is parity-alternating if it sends even integers to even integers, and odd integers to odd. I am ...
Per Alexandersson's user avatar
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The meet of two dominant permutations in weak order of $S_n$

A permutation is called dominant if its Lehmer code is a partition, or equivalently if it avoids the pattern $132$. I can prove that given a permutation $v\in S_n$, there is a unique dominant ...
Matt Samuel's user avatar
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Permutations avoiding a family of consecutive patterns

Let $B=\{1324,14325,154326,1654327,\ldots\}$ be the set of permutation patterns of the form $1(m-1)(m-2)\cdots 2m$ for $m\geq 4$. I'm interested in the set $\mathcal P$ of permutations that avoid all ...
Colin Defant's user avatar