Arunkumar, G (2021) Chromatic symmetric function of graphs from Borcherds algebras. In: Journal of Combinatorial Theory. Series A, 183 .

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Abstract
The Weyl denominator identity has interesting combinatorial properties for several classes of Lie algebras. Along these lines, we prove that given a finite graph G, the chromatic symmetric function XG can be recovered from the Weyl denominator identity of a BorcherdsKacMoody Lie algebra g whose associated graph is G. This gives a connection between (a) the coefficients appearing when the chromatic symmetric function XG is expressed in terms of the power sum symmetric functions, and (b) the root multiplicities of the Borcherds algebra g. From this result, we deduce a Lie theoretic proof of various alternate expressions of the chromatic symmetric function obtained by Stanley. Examples using small rank Lie algebras are provided to illustrate our results. The absolute value of the linear coefficient of the chromatic polynomial of G is known as the chromatic discriminant of G. As an application of our main theorem, we identify a coefficient appearing in XG, which equals the chromatic discriminant. We also find a connection between the Weyl denominator and the Gelementary symmetric functions. Using this connection, we give a Lie theoretic proof of the nonnegativity of coefficients of Gpower sum symmetric functions.
Item Type:  Journal Article 

Publication:  Journal of Combinatorial Theory. Series A 
Publisher:  Academic Press Inc. 
Additional Information:  The copyright for this article belongs to the Authors. 
Keywords:  Borcherds algebras; Chromatic symmetric functions; Free partially commutative Lie algebras; Gsymmetric functions; Weyl denominator identity 
Department/Centre:  Division of Physical & Mathematical Sciences > Mathematics 
Date Deposited:  05 Jun 2023 10:51 
Last Modified:  05 Jun 2023 10:51 
URI:  https://eprints.iisc.ac.in/id/eprint/81772 
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