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We introduce $H$-chromatic symmetric functions, $X_{G}^{H}$, which use the $H$-coloring of a graph $G$ to define a generalization of Stanley's chromatic symmetric functions. We say two graphs $G_1$ and $G_2$ are $H$-chromatically equivalent…

Combinatorics · Mathematics 2022-05-23 Nancy Mae Eagles , Angèle M. Foley , Alice Huang , Elene Karangozishvili , Annan Yu

The chromatic symmetric function $X_G$ is a sum of monomials corresponding to proper vertex colorings of a graph $G$. Crew, Pechenik, and Spirkl (2023) recently introduced a $K$-theoretic analogue $\overline{X}_G$ called the Kromatic…

Combinatorics · Mathematics 2025-02-21 Laura Pierson

Let $T$ be an unrooted tree. The \emph{chromatic symmetric function} $X_T$, introduced by Stanley, is a sum of monomial symmetric functions corresponding to proper colorings of $T$. The \emph{subtree polynomial} $S_T$, first considered…

Combinatorics · Mathematics 2011-10-05 Jeremy L. Martin , Matthew Morin , Jennifer D. Wagner

We study the $H$-chromatic symmetric functions $X_G^H$ (introduced in (arXiv:2011.06063) as a generalization of the chromatic symmetric function (CSF) $X_G$), which track homomorphisms from the graph $G$ to the graph $H$. We focus first on…

Combinatorics · Mathematics 2025-11-13 Shao Yuan Lin , Laura Pierson

Stanley [9] introduced the chromatic symmetric function ${\bf X}_G$ associated to a simple graph $G$ as a generalization of the chromatic polynomial of $G$. In this paper we present a novel technique to write ${\bf X}_G$ as a linear…

Combinatorics · Mathematics 2013-08-29 Rosa Orellana , Geoffrey Scott

We investigate the problem of when a chromatic quasisymmetric function (CQF) $X_G(x;q)$ of a graph $G$ is in fact symmetric. We first prove the remarkable fact that if a product of two quasisymmetric functions $f$ and $g$ in countably…

Combinatorics · Mathematics 2025-08-04 Maria Gillespie , Joseph Pappe , Kyle Salois

The chromatic symmetric function $X_G$ is a power series that encodes the proper colorings of a graph $G$ by assigning a variable to each color and a monomial to each coloring such that the power of a variable in a monomial is the number of…

Combinatorics · Mathematics 2024-08-05 Laura Pierson

We study the chromatic symmetric function on graphs, and show that its kernel is spanned by the modular relations. We generalize this result to the chromatic quasisymmetric function on hypergraphic polytopes, a family of generalized…

Combinatorics · Mathematics 2020-03-31 Raul Penaguiao

Richard P. Stanley defined the chromatic symmetric function of a simple graph and has conjectured that every tree is determined by its chromatic symmetric function. Recently, Takahiro Hasebe and the author proved that the order…

Combinatorics · Mathematics 2018-07-23 Shuhei Tsujie

We prove some Schur positivity results for the chromatic symmetric function $X_G$ of a (hyper)graph $G$, using connections to the group algebra of the symmetric group. The first such connection works for (hyper)forests $F$: we describe the…

Combinatorics · Mathematics 2024-10-29 Brendan Pawlowski

We define vertex-colourings for edge-partitioned digraphs, which unify the theory of P-partitions and proper vertex-colourings of graphs. We use our vertex-colourings to define generalized chromatic functions, which merge the chromatic…

Combinatorics · Mathematics 2023-06-28 Farid Aliniaeifard , Shu Xiao Li , Stephanie van Willigenburg

We study the chromatic quasisymmetric class function of a linearized combinatorial Hopf monoid. Given a linearized combinatorial Hopf monoid $H$, and an $H$-structure $h$ on a set $N$, there are proper colorings of $h$, generalizing graph…

Combinatorics · Mathematics 2022-10-11 Jacob A. White

A MacMahon symmetric function is an invariant of the diagonal action of the symmetric group on power series in multiple alphabets of variables. We introduce an analogue of the chromatic symmetric function for vertex-weighted graphs, taking…

Combinatorics · Mathematics 2025-08-04 Jeremy L. Martin , May B. Trist

A C-coloring of a hypergraph ${\cal H}=(X,{\cal E})$ is a vertex coloring $\varphi: X\to {\mathbb{N}}$ such that each edge $E\in{\cal E}$ has at least two vertices with a common color. The related parameter $\overline{\chi}({\cal H})$,…

Combinatorics · Mathematics 2013-10-31 Csilla Bujtás , Zsolt Tuza

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

Two celebrated conjectures in chromatic symmetric function theory concern the positivity chromatics symmetric functions of claw-free graphs. Here we extend the claw-free idea to general graphs and consider the e-positivity question for…

Combinatorics · Mathematics 2017-09-12 Angèle M. Hamel , Chính T. Hoàng , Jake E. Tuero

The chromatic symmetric function of a graph is a generalization of the chromatic polynomial. The key motivation for studying the structure of a chromatic symmetric function is to answer positivity conjectures by Stanley in 1995 and Gasharov…

Combinatorics · Mathematics 2014-11-10 Ryan Kaliszewski

Schur functions are a basis of the symmetric function ring that represent Schubert cohomology classes for Grassmannians. Replacing the cohomology ring with $K$-theory yields a rich combinatorial theory of inhomogeneous deformations, where…

Combinatorics · Mathematics 2023-05-19 Logan Crew , Oliver Pechenik , Sophie Spirkl

In 1995, Stanley introduced the well-known chromatic symmetric function $X_{G}(x_{1},x_{2},\ldots)$ of a graph $G$. It is a sum of monomial symmetric functions such that for each vertex coloring of $G$ there is exactly one of these…

Combinatorics · Mathematics 2017-02-28 Melanie Gerling

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
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