The Chromatic Symmetric Function for Unicyclic Graphs

Fuente: arXiv
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Autori principali: Bingham, Aram, Johnston, Lisa, Lawson, Colin, Orellana, Rosa, Pan, Jianping, Sato, Chelsea
Natura: Preprint
Pubblicazione: 2025
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author Bingham, Aram
Johnston, Lisa
Lawson, Colin
Orellana, Rosa
Pan, Jianping
Sato, Chelsea
author_facet Bingham, Aram
Johnston, Lisa
Lawson, Colin
Orellana, Rosa
Pan, Jianping
Sato, Chelsea
contents Motivated by the question of which structural properties of a graph can be recovered from the chromatic symmetric function (CSF), we study the CSF of connected unicyclic graphs. While it is known that there can be non-isomorphic unicyclic graphs with the same CSF, we find experimentally that such examples are rare for graphs with up to 17 vertices. In fact, in many cases we can recover data such as the number of leaves, number of internal edges, cycle size, and number of attached non-trivial trees, by extending known results for trees to unicyclic graphs. These results are obtained by analyzing the CSF of a connected unicyclic graph in the $\textit{star-basis}$ using the deletion-near-contraction (DNC) relation developed by Aliste-Prieto, Orellana and Zamora, and computing the "leading" partition, its coefficient, as well as coefficients indexed by hook partitions. We also give explicit formulas for star-expansions of several classes of graphs, developing methods for extracting coefficients using structural properties of the graph.
format Preprint
id arxiv_https___arxiv_org_abs_2505_06486
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Chromatic Symmetric Function for Unicyclic Graphs
Bingham, Aram
Johnston, Lisa
Lawson, Colin
Orellana, Rosa
Pan, Jianping
Sato, Chelsea
Combinatorics
05E05, 05C60
Motivated by the question of which structural properties of a graph can be recovered from the chromatic symmetric function (CSF), we study the CSF of connected unicyclic graphs. While it is known that there can be non-isomorphic unicyclic graphs with the same CSF, we find experimentally that such examples are rare for graphs with up to 17 vertices. In fact, in many cases we can recover data such as the number of leaves, number of internal edges, cycle size, and number of attached non-trivial trees, by extending known results for trees to unicyclic graphs. These results are obtained by analyzing the CSF of a connected unicyclic graph in the $\textit{star-basis}$ using the deletion-near-contraction (DNC) relation developed by Aliste-Prieto, Orellana and Zamora, and computing the "leading" partition, its coefficient, as well as coefficients indexed by hook partitions. We also give explicit formulas for star-expansions of several classes of graphs, developing methods for extracting coefficients using structural properties of the graph.
title The Chromatic Symmetric Function for Unicyclic Graphs
topic Combinatorics
05E05, 05C60
url https://arxiv.org/abs/2505.06486