English

A deletion-contraction long exact sequence for chromatic symmetric homology

Combinatorics 2023-08-08 v2 Algebraic Topology Representation Theory

Abstract

Crew and Spirklt generalize Stanley's chromatic symmetric function to vertex-weighted graphs. One of the primary motivations for extending the chromatic symmetric function to vertex-weighted graphs is the existence of a deletion-contraction relation in this setting, which, as known, holds for the chromatic polynomial, but doesn't hold for the chromatic symmetric function. In this paper we find a categorification of their new invariant extending the definition of chromatic symmetric homology to vertex-weighted graphs. We prove the existence of a deletion-contraction long exact sequence for chromatic symmetric homology which lifts the deletion-contraction relation that holds for the extension of Crew and Spirklt. Moreover, the new categorification gives a useful computational tool and allow us to answer two questions left open by Chandler, Sazdanovic, Stella and Yip. In particular, we prove that, for a graph G with nn vertices, the maximal index with nonzero homology is not greater that nn - 1. Moreover, we show that the homology is non-trivial for all the indices between the minimum and the maximum with this property.

Keywords

Cite

@article{arxiv.2211.00699,
  title  = {A deletion-contraction long exact sequence for chromatic symmetric homology},
  author = {Azzurra Ciliberti},
  journal= {arXiv preprint arXiv:2211.00699},
  year   = {2023}
}

Comments

18 pages; to appear in European Journal of Combinatorics