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The chromatic symmetric function $X_G$ of a graph $G$ was introduced by Stanley. In this paper we introduce a quasisymmetric generalization $X^k_G$ called the $k$-chromatic quasisymmetric function of $G$ and show that it is positive in the…

Combinatorics · Mathematics 2011-01-05 Brandon Humpert

We prove necessary conditions for certain elementary symmetric functions, $e_\lambda$, to appear with nonzero coefficient in Stanley's chromatic symmetric function as well as in the generalization considered by Shareshian and Wachs. We do…

Combinatorics · Mathematics 2024-07-09 Bruce E. Sagan , Foster Tom

The Stanley chromatic symmetric function $X_G$ of a graph $G$ is a symmetric function generalization of the chromatic polynomial, and has interesting combinatorial properties. We apply the ideas of Khovanov homology to construct a homology…

Combinatorics · Mathematics 2015-06-11 Radmila Sazdanovic , Martha Yip

In this paper, we extend the chromatic symmetric function $X$ to a chromatic $k$-multisymmetric function $X_k$, defined for graphs equipped with a partition of their vertex set into $k$ parts. We demonstrate that this new function retains…

Combinatorics · Mathematics 2022-09-29 Logan Crew , Evan Haithcock , Josephine Reynes , Sophie Spirkl

In this paper, we introduce the \emph{$\alpha$-chromatic symmetric functions} $\chi^{(\alpha)}_\pi[X;q]$, extending Shareshian and Wachs' chromatic symmetric functions with an additional real parameter $\alpha$. We present positive…

Combinatorics · Mathematics 2025-04-21 Jim Haglund , Jaeseong Oh , Meesue Yoo

We give a proof of Stanley-Stembridge conjecture on chromatic symmetric functions for the class of all unit interval graphs with independence number 3. That is, we show that the chromatic symmetric function of the incomparability graph of a…

Combinatorics · Mathematics 2022-04-27 Soojin Cho , Jaehyun Hong

We extend the definition of the chromatic symmetric function $X_G$ to include graphs $G$ with a vertex-weight function $w : V(G) \rightarrow \mathbb{N}$. We show how this provides the chromatic symmetric function with a natural…

Combinatorics · Mathematics 2020-01-16 Logan Crew , Sophie Spirkl

J. Makowsky and B. Zilber (2004) showed that many variations of graph colorings, called CP-colorings in the sequel, give rise to graph polynomials. This is true in particular for harmonious colorings, convex colorings, mcc_t-colorings, and…

Combinatorics · Mathematics 2017-01-25 A. Goodall , M. Hermann , T. Kotek , J. A. Makowsky , S. D. Noble

Crew and Spirklt generalize Stanley's chromatic symmetric function to vertex-weighted graphs. One of the primary motivations for extending the chromatic symmetric function to vertex-weighted graphs is the existence of a deletion-contraction…

Combinatorics · Mathematics 2023-08-08 Azzurra Ciliberti

In 1995, Stanley introduced the chromatic symmetric function of a graph, which specializes to its chromatic polynomial, and which has been the focus of intense research. In 2017, Shareshian, Wachs, and Ellzey defined a refinement of this…

Combinatorics · Mathematics 2025-08-29 Jean-Christophe Aval , Raquel Melgar

By using level one polynomial representations of affine Hecke algebras of type $A$, we obtain a $(q,t)$-analogue of the chromatic symmetric functions of unit interval graphs which generalizes Syu Kato's formula for the chromatic symmetric…

Combinatorics · Mathematics 2025-04-01 Tatsuyuki Hikita

Plethysm is a fundamental operation in symmetric function theory, derived directly from its connection with representation theory. However, it does not admit a simple combinatorial interpretation, and finding coefficients of Schur function…

Combinatorics · Mathematics 2022-08-03 Logan Crew , Sophie Spirkl

In 1995 Stanley introduced a generalization of the chromatic polynomial of a graph $G$, called the chromatic symmetric function, $X_G$, which was generalized to noncommuting variables, $Y_G$, by Gebhard-Sagan in 2001. Recently there has…

Combinatorics · Mathematics 2019-12-17 Samantha Dahlberg , Stephanie van Willigenburg

In 1995 Stanley introduced the chromatic symmetric function $X_G$ of a graph $G$, whose $e$-positivity and Schur-positivity has been of large interest. In this paper we study the relative $e$-positivity and Schur-positivity between…

Combinatorics · Mathematics 2020-03-16 Samantha Dahlberg , Adrian She , Stephanie van Willigenburg

In this paper, we study positivity phenomena for the $e$-coefficients of Stanley's chromatic function of a graph. We introduce a new combinatorial object: the {\em correct} sequences of unit interval orders, and using these, in certain…

Combinatorics · Mathematics 2017-03-20 Alexander Paunov , András Szenes

We give a probabilistic interpretation of the coefficients of the elementary symmetric function expansion of the chromatic quasisymmetric function for any unit interval graph. As a corollary, we prove the Stanley--Stembridge conjecture.

Combinatorics · Mathematics 2025-12-29 Tatsuyuki Hikita

Chromatic quasisymmetric functions of labeled graphs were defined by Shareshian and Wachs as a refinement of Stanley's chromatic symmetric functions. In this extended abstract, we consider an extension of their definition from labeled…

Combinatorics · Mathematics 2017-04-17 Brittney Ellzey

In 1993, Stanley and Stembridge conjectured that a chromatic symmetric function of any $(3+1)$-free poset is $e$-positive. Guay-Paquet reduced the conjecture to $(3+1)$- and $(2+2)$-free posets which are also called natural unit interval…

Combinatorics · Mathematics 2022-02-15 Seung Jin Lee , Sue Kyong Y. Soh

The chromatic quasisymmetric functions (csf) of Shareshian and Wachs associated to unit interval orders have attracted a lot of interest since their introduction in 2016, both in combinatorics and geometry, because of their relation to the…

Combinatorics · Mathematics 2023-11-17 Michele D'Adderio , Roberto Riccardi , Viola Siconolfi

In this paper, we introduce and study two variants of the chromatic quasisymmetric function of a graph: the total chromatic quasisymmetric function via vertex labeling and via acyclic orientations. The original definition of the chromatic…

Combinatorics · Mathematics 2026-02-27 Laura Colmenarejo , Ian Klein