On Macdonald expansions of $q$-chromatic symmetric functions and the Stanley-Stembridge Conjecture

Fuente: arXiv
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Main Authors: Griffin, Sean T., Mellit, Anton, Romero, Marino, Weigl, Kevin, Wen, Joshua Jeishing
Format: Preprint
Published: 2025
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author Griffin, Sean T.
Mellit, Anton
Romero, Marino
Weigl, Kevin
Wen, Joshua Jeishing
author_facet Griffin, Sean T.
Mellit, Anton
Romero, Marino
Weigl, Kevin
Wen, Joshua Jeishing
contents The Stanley-Stembridge conjecture asserts that the chromatic symmetric function of a $(3+1)$-free graph is $e$-positive. Recently, Hikita proved this conjecture by giving an explicit $e$-expansion of the Shareshian-Wachs $q$-chromatic refinement for unit interval graphs. Using the $\mathbb{A}_{q,t}$ algebra, we give an expansion of these $q$-chromatic symmetric functions into Macdonald polynomials. Upon setting $t=1$, we obtain another proof of the Stanley-Stembridge conjecture and rederive Hikita's formula. Upon setting $t=0$, we obtain an expansion into Hall-Littlewood symmetric functions.
format Preprint
id arxiv_https___arxiv_org_abs_2504_06936
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Macdonald expansions of $q$-chromatic symmetric functions and the Stanley-Stembridge Conjecture
Griffin, Sean T.
Mellit, Anton
Romero, Marino
Weigl, Kevin
Wen, Joshua Jeishing
Combinatorics
Representation Theory
The Stanley-Stembridge conjecture asserts that the chromatic symmetric function of a $(3+1)$-free graph is $e$-positive. Recently, Hikita proved this conjecture by giving an explicit $e$-expansion of the Shareshian-Wachs $q$-chromatic refinement for unit interval graphs. Using the $\mathbb{A}_{q,t}$ algebra, we give an expansion of these $q$-chromatic symmetric functions into Macdonald polynomials. Upon setting $t=1$, we obtain another proof of the Stanley-Stembridge conjecture and rederive Hikita's formula. Upon setting $t=0$, we obtain an expansion into Hall-Littlewood symmetric functions.
title On Macdonald expansions of $q$-chromatic symmetric functions and the Stanley-Stembridge Conjecture
topic Combinatorics
Representation Theory
url https://arxiv.org/abs/2504.06936