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arXiv 1809.07398math.CO
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关于置换权与$q$ -欧拉多项式

On Permutation Weights and $q$-Eulerian Polynomials

Aman Agrawal, Caroline Choi, Nathan Sun

摘要:

排列的权重最初由Dugan,Glennon,Gunnells和Steingrímsson(组合理论杂志,系列A 164:24-49,2019)在他们对分层树的组合学的研究中引入。给定被视为整数序列的置换$σ$,计算$σ$的权重涉及递归地计数$σ$的某些子置换的下降。使用该权函数,可以定义欧拉多项式的$q$ -模拟$E_n(x,q)$。我们证明了两个主要结果的重量置换和多项式$E_n(x,q)$。首先,我们证明了$E_n(x, q)$的系数在$n$趋于无穷大时稳定,这是由Dugan,Glennon,Gunnells和Steingrímsson(组合理论杂志,系列A 164:24-49,2019)证明的,并允许定义形式幂级数$W_d(t)$,它具有有趣的组合性质。其次,我们推导出一个递归关系的$E_n(x, q)$,类似于已知的递归的经典欧拉多项式$A_n(x)$。最后,我们给出了某些整数分拆个数的递推公式,并由此推测了上述稳定系数的递推公式。

英文摘要:

Weights of permutations were originally introduced by Dugan, Glennon, Gunnells, and Steingrímsson (Journal of Combinatorial Theory, Series A 164:24-49, 2019) in their study of the combinatorics of tiered trees. Given a permutation $σ$ viewed as a sequence of integers, computing the weight of $σ$ involves recursively counting descents of certain subpermutations of $σ$. Using this weight function, one can define a $q$-analog $E_n(x,q)$ of the Eulerian polynomials. We prove two main results regarding weights of permutations and the polynomials $E_n(x,q)$. First, we show that the coefficients of $E_n(x, q)$ stabilize as $n$ goes to infinity, which was conjectured by Dugan, Glennon, Gunnells, and Steingrímsson (Journal of Combinatorial Theory, Series A 164:24-49, 2019), and enables the definition of the formal power series $W_d(t)$, which has interesting combinatorial properties. Second, we derive a recurrence relation for $E_n(x, q)$, similar to the known recurrence for the classical Eulerian polynomials $A_n(x)$. Finally, we give a recursive formula for the numbers of certain integer partitions and, from this, conjecture a recursive formula for the stabilized coefficients mentioned above.

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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