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arXiv 2407.06155math.CO
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色对称函数与基变换

Chromatic symmetric functions and change of basis

Bruce E. Sagan, Foster Tom

AI总结:

本文通过单项式基与 Schur 基的展开及基变换,证明了色对称函数中初等对称函数非零系数的必要条件,并给出自然单位区间图三列系数非负性及 $e_n$ 系数的显式公式。

摘要:

我们证明了某些初等对称函数 $e_λ$ 在 Stanley 色对称函数以及 Shareshian 和 Wachs 所考虑的推广中以非零系数出现的必要条件。我们首先考虑单项式基或 Schur 基中的展开,然后进行基变换。利用前者,我们建立了与两个基本图论不变量——独立数和团数——的联系。这使我们能够证明所有自然单位区间图的三列系数的非负性。Schur 基使我们能够用表(tableaux)对 $e_n$ 的系数给出一种新的解释。我们还能够给出该系数的显式公式。

英文摘要:

We prove necessary conditions for certain elementary symmetric functions, $e_λ$, to appear with nonzero coefficient in Stanley's chromatic symmetric function as well as in the generalization considered by Shareshian and Wachs. We do this by first considering the expansion in the monomial or Schur basis and then performing a basis change. Using the former, we make a connection with two fundamental graph theory invariants, the independence and clique numbers. This allows us to prove nonnegativity of three-column coefficients for all natural unit interval graphs. The Schur basis permits us to give a new interpretation of the coefficient of $e_n$ in terms of tableaux. We are also able to give an explicit formula for that coefficient.

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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