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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

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

A natural unit interval order is a naturally labelled partially ordered set that avoids patterns ${\bf 3} + {\bf 1}$ and $\bf 2 + 2$. To each natural unit interval order one can associate a symmetric function. The Stanley-Stembridge…

Combinatorics · Mathematics 2024-04-23 Joseph McDonough , Pavlo Pylyavskyy , Shiyun Wang

Chromatic symmetric functions are well-studied symmetric functions in algebraic combinatorics that generalize the chromatic polynomial and are related to Hessenberg varieties and diagonal harmonics. Motivated by the Stanley--Stembridge…

Combinatorics · Mathematics 2025-02-11 Jacob P. Matherne , Alejandro H. Morales , Jesse Selover

Stanley introduces polynomials which help evaluate symmetric group characters and conjectures that the coefficients of the polynomials are positive. Stanley later gives a conjectured combinatorial interpretation for the coefficients of the…

Combinatorics · Mathematics 2007-12-21 Amarpreet Rattan

We give a short proof of the chromatic e-positivity conjecture of Stanley for length-2 partitions.

Combinatorics · Mathematics 2023-05-02 Alexandre Rok , Andras Szenes

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 Stanley-Stembridge conjecture associates a symmetric function to each natural unit interval order $\mathcal P$. In this paper, we define relations \`a la Knuth on the symmetric group for each $\mathcal P$ and conjecture that the…

Combinatorics · Mathematics 2020-05-15 Dongkwan Kim , Pavlo Pylyavskyy

The chromatic quasisymmetric function of a graph was introduced by Shareshian and Wachs as a refinement of Stanley's chromatic symmetric function. An explicit combinatorial formula, conjectured by Shareshian and Wachs, expressing the…

Combinatorics · Mathematics 2015-04-28 Christos A. Athanasiadis

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

The U-polynomial, the polychromate and the symmetric function generalization of the Tutte polynomial due to Stanley are known to be equivalent in the sense that the coefficients of any one of them can be obtained as a function of the…

Combinatorics · Mathematics 2008-06-02 Criel Merino , Steven D. Noble

A famous conjecture of Stanley states that his chromatic symmetric function distinguishes trees. As a quasisymmetric analogue, we conjecture that the chromatic quasisymmetric function of Shareshian and Wachs and of Ellzey distinguishes…

Combinatorics · Mathematics 2024-12-09 Jean-Christophe Aval , Karimatou Djenabou , Peter R. W. McNamara

For each indifference graph, there is an associated regular semisimple Hessenberg variety, whose cohomology recovers the chromatic symmetric function of the graph. The decomposition theorem applied to the forgetful map from the regular…

Algebraic Geometry · Mathematics 2023-04-24 Alex Abreu , Antonio Nigro

We discover new linear relations between the chromatic symmetric functions of certain sequences of graphs and apply these relations to find new families of e-positive unit interval graphs. Motivated by the results of Gebhard and Sagan, we…

Combinatorics · Mathematics 2024-12-24 Farid Aliniaeifard , Victor Wang , Stephanie van Willigenburg

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

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

Stanley defined the chromatic symmetric function of a graph, and Shareshian and Wachs introduced a refinement, namely the chromatic quasisymmetric function of a labeled graph. In this paper, we define the chromatic quasisymmetric function…

Combinatorics · Mathematics 2017-09-07 Brittney Ellzey

In the mid-1990s, Stanley and Stembridge conjectured that the chromatic symmetric functions of claw-free co-comparability (also called incomparability) graphs were e-positive. The quest for the proof of this conjecture has led to an…

Combinatorics · Mathematics 2018-08-13 Angèle M. Foley , Chính T. Hoàng , Owen D. Merkel

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

We discuss three distinct topics of independent interest; one in enumerative combinatorics, one in symmetric function theory, and one in algebraic geometry. The topic in enumerative combinatorics concerns a q-analog of a generalization of…

Combinatorics · Mathematics 2012-07-09 John Shareshian , Michelle L. Wachs