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Related papers: Kromatic quasisymmetric functions

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If we consider previously introduced extensions of Stanley's chromatic symmetric function $X_{G}(x_1, x_2, \ldots)$ for a graph $G$ to elements in the algebra $\textsf{QSym}$ of quasisymmetric functions and in the algebra $\textsf{NCSym}$…

Combinatorics · Mathematics 2024-10-08 John M. Campbell

We introduce analogues of the Hopf algebra of Free quasi-symmetric functions with bases labelled by colored permutations. As applications, we recover in a simple way the descent algebras associated with wreath products $\Gamma\wr\SG_n$ and…

Combinatorics · Mathematics 2007-05-23 Jean-Christophe Novelli , Jean-Yves Thibon

Eulerian quasisymmetric functions were introduced by Shareshian and Wachs in order to obtain a q-analog of Euler's exponential generating function formula for the Eulerian numbers. They are defined via the symmetric group, and applying the…

Combinatorics · Mathematics 2012-05-07 Matthew Hyatt

This article serves as an introduction to several recent developments in the study of quasisymmetric functions. The focus of this survey is on connections between quasisymmetric functions and the combinatorial Hopf algebra of noncommutative…

Combinatorics · Mathematics 2018-10-17 Sarah K. Mason

We introduce dual Hopf algebras which simultaneously combine the concepts of the k-Schur function theory with the quasi-symmetric Schur function theory. We construct dual basis of these Hopf algebras with remarkable properties.

Combinatorics · Mathematics 2012-05-11 Chris Berg , Luis Serrano

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

We prove a new signed elementary symmetric function expansion of the chromatic quasisymmetric function of any natural unit interval graph. We then use a sign-reversing involution to prove a new combinatorial formula for K-chains, which are…

Combinatorics · Mathematics 2024-05-09 Foster Tom

We introduce path-conjoined graphs defined for two rooted graphs by joining their roots with a path, and investigate the chromatic symmetric functions of its two generalizations: spider-conjoined graphs and chain-conjoined graphs. By using…

Combinatorics · Mathematics 2026-02-04 E. Y. J. Qi , D. Q. B. Tang , D. G. L. Wang

We prove a general inclusion-exclusion relation for the extended chromatic symmetric function of a weighted graph, which specializes to (extended) $k$-deletion, and we give two methods to obtain numerous new bases from weighted graphs for…

Combinatorics · Mathematics 2021-03-29 Farid Aliniaeifard , Victor Wang , Stephanie van Willigenburg

We study the symmetric function and polynomial combinatorial invariants of Hopf algebras of permutations, posets and graphs. We investigate their properties and the relations among them. In particular, we show that the chromatic symmetric…

Combinatorics · Mathematics 2020-10-01 Jean-christophe Aval , Nantel Bergeron , John Machacek

In this article we show how to compute the chromatic quasisymmetric function of indifference graphs from the modular law introduced by Guay-Paquet. We provide an algorithm which works for any function that satisfies this law, such as…

Combinatorics · Mathematics 2020-06-23 Alex Abreu , Antonio Nigro

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

Like its precursor this paper is concerned with the Hopf algebra of noncommutative symmetric functions and its graded dual, the Hopf algebra of quasisymmetric functions. It complements and extends the previous paper but is also…

Quantum Algebra · Mathematics 2007-05-23 Michiel Hazewinkel

In our previous works we introduced a $q$-deformation of the generating functions for enriched $P$-partitions. We call the evaluation of this generating functions on labelled chains, the $q$-fundamental quasisymmetric functions. These…

Combinatorics · Mathematics 2024-10-30 Darij Grinberg , Ekaterina A. Vassilieva

As proved by Kahn, the chromatic number and fractional chromatic number of a line graph agree asymptotically. That is, for any line graph $G$ we have $\chi(G) \leq (1+o(1))\chi_f(G)$. We extend this result to quasi-line graphs, an important…

Discrete Mathematics · Computer Science 2011-02-07 Andrew D. King , Bruce Reed

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

The $e$-positivity conjecture and the $e$-unimodality conjecture of chromatic quasisymmetric functions are proved for some classes of natural unit interval orders. Recently, J. Shareshian and M. Wachs introduced chromatic quasisymmetric…

Combinatorics · Mathematics 2017-11-28 Soojin Cho , JiSun Huh

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

We introduce a quasisymmetric generalization of Berele and Regev's hook Schur functions and prove that these new quasisymmetric hook Schur functions decompose the hook Schur functions in a natural way. We examine the combinatorics of the…

Combinatorics · Mathematics 2016-06-23 Sarah K Mason , Elizabeth Niese

This is a set of working notes which give a second proof of the Shareshian--Wachs conjecture, the first (and recent) proof being by Brosnan and Chow in November 2015. The conjecture relates some symmetric functions constructed…

Combinatorics · Mathematics 2016-01-22 Mathieu Guay-Paquet