The chromatic symmetric function of graphs glued at a single vertex

Fuente: arXiv
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Autori principali: Tom, Foster, Vailaya, Aarush
Natura: Preprint
Pubblicazione: 2025
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author Tom, Foster
Vailaya, Aarush
author_facet Tom, Foster
Vailaya, Aarush
contents We describe how the chromatic symmetric function of two graphs glued at a single vertex can be expressed as a matrix multiplication using certain information of the two individual graphs. We then prove new $e$-positivity results by using a connection between forest triples, defined by the first author, and Hikita's probabilities associated to standard Young tableaux. Specifically, we prove that gluing a sequence of unit interval graphs and cycles results in an $e$-positive graph. We also prove $e$-positivity for a graph obtained by gluing the first and last vertices of such a sequence. This generalizes $e$-positivity of cycle-chord graphs and supports Ellzey's conjectured $e$-positivity for proper circular arc digraphs.
format Preprint
id arxiv_https___arxiv_org_abs_2503_19344
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The chromatic symmetric function of graphs glued at a single vertex
Tom, Foster
Vailaya, Aarush
Combinatorics
Primary 05E05, Secondary 05E10, 05C15
We describe how the chromatic symmetric function of two graphs glued at a single vertex can be expressed as a matrix multiplication using certain information of the two individual graphs. We then prove new $e$-positivity results by using a connection between forest triples, defined by the first author, and Hikita's probabilities associated to standard Young tableaux. Specifically, we prove that gluing a sequence of unit interval graphs and cycles results in an $e$-positive graph. We also prove $e$-positivity for a graph obtained by gluing the first and last vertices of such a sequence. This generalizes $e$-positivity of cycle-chord graphs and supports Ellzey's conjectured $e$-positivity for proper circular arc digraphs.
title The chromatic symmetric function of graphs glued at a single vertex
topic Combinatorics
Primary 05E05, Secondary 05E10, 05C15
url https://arxiv.org/abs/2503.19344