A parking function interpretation for $(-1)^{k}\nabla m_{2^{k}1^{l}}$

Fuente: arXiv
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Autori principali: Qu, Menghao, Xin, Guoce
Natura: Preprint
Pubblicazione: 2023
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author Qu, Menghao
Xin, Guoce
author_facet Qu, Menghao
Xin, Guoce
contents Haglund, Morse, and Zabrocki introduced a family of creation operators of Hall-Littlewood polynomials, $\{C_{a}\}$ for any $a\in \mathbb{Z}$, in their compositional refinement of the shuffle (ex-)conjecture. For any $α\vDash n$, the combinatorial formula for $\nabla C_α$ is a weighted sum of parking functions. These summations can be converted to a weighted sum of certain LLT polynomials. Thus $\nabla C_α$ is Schur positive since Grojnowski and Haiman proved that all LLT polynomials are Schur positive. In this paper, we obtain a recursion that implies the $C$-positivity of $(-1)^{k} m_{2^{k}1^{l}}$, and hence prove the Schur positivity of $(-1)^{k}\nabla m_{2^{k}1^{l}}$. As a corollary, a parking function interpretation for $(-1)^{k}\nabla m_{2^{k}1^{l}}$ is obtained by using the compositional shuffle theorem of Carlsson and Mellit.
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id arxiv_https___arxiv_org_abs_2312_16824
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A parking function interpretation for $(-1)^{k}\nabla m_{2^{k}1^{l}}$
Qu, Menghao
Xin, Guoce
Combinatorics
Haglund, Morse, and Zabrocki introduced a family of creation operators of Hall-Littlewood polynomials, $\{C_{a}\}$ for any $a\in \mathbb{Z}$, in their compositional refinement of the shuffle (ex-)conjecture. For any $α\vDash n$, the combinatorial formula for $\nabla C_α$ is a weighted sum of parking functions. These summations can be converted to a weighted sum of certain LLT polynomials. Thus $\nabla C_α$ is Schur positive since Grojnowski and Haiman proved that all LLT polynomials are Schur positive. In this paper, we obtain a recursion that implies the $C$-positivity of $(-1)^{k} m_{2^{k}1^{l}}$, and hence prove the Schur positivity of $(-1)^{k}\nabla m_{2^{k}1^{l}}$. As a corollary, a parking function interpretation for $(-1)^{k}\nabla m_{2^{k}1^{l}}$ is obtained by using the compositional shuffle theorem of Carlsson and Mellit.
title A parking function interpretation for $(-1)^{k}\nabla m_{2^{k}1^{l}}$
topic Combinatorics
url https://arxiv.org/abs/2312.16824