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arXiv 2004.09198math.COmath.RT
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初等对称函数基下竖直带LLT多项式的组合展开

A combinatorial expansion of vertical-strip LLT polynomials in the basis of elementary symmetric functions

Per Alexandersson, Robin Sulzgruber

AI总结:

该研究给出竖直带LLT多项式的新组合刻画,证明其按初等对称函数的显式组合展开式,验证相关猜想并重现已有显正性结果,还得到单位区间图色拟对称函数的新刻画。

摘要:

我们给出竖直带LLT多项式$\text{LLT}_P(x;q)$的一种新刻画:它是满足特定组合关系的唯一对称函数族。随后利用该刻画,证明了竖直带LLT多项式按初等对称函数的显式组合展开式。这类公式由A. Garsia等人与第一作者独立提出猜想,其规律由单位区间图的定向组合学支配。将$q$替换为$q+1$后,所得展开式具有显正性,由此重现了M. D'Adderio的近期结果。我们的研究基于D'Adderio以及E. Carlsson和A. Mellit工作中提出的LLT多项式之间的线性关系;在一定程度上,我们利用单位区间图的着色为这些关系给出了新的双射证明。作为附加成果,我们得到了单位区间图的色拟对称函数的一种新刻画。

英文摘要:

We give a new characterization of the vertical-strip LLT polynomials $\mathrm{LLT}_P(x;q)$ as the unique family of symmetric functions that satisfy certain combinatorial relations. This characterization is then used to prove an explicit combinatorial expansion of vertical-strip LLT polynomials in terms of elementary symmetric functions. Such formulas were conjectured independently by A. Garsia et al. and the first named author, and are governed by the combinatorics of orientations of unit-interval graphs. The obtained expansion is manifestly positive if $q$ is replaced by $q+1$, thus recovering a recent result of M. D'Adderio. Our results are based on linear relations among LLT polynomials that arise in the work of D'Adderio, and of E. Carlsson and A. Mellit. To some extent these relations are given new bijective proofs using colorings of unit-interval graphs. As a bonus we obtain a new characterization of chromatic quasisymmetric functions of unit-interval graphs.

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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