Splines on Cayley Graphs of the Symmetric Group

Fuente: arXiv
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Main Author: Lesnevich, Nathan R. T.
Format: Preprint
Published: 2024
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author Lesnevich, Nathan R. T.
author_facet Lesnevich, Nathan R. T.
contents A spline is an assignment of polynomials to the vertices of a graph whose edges are labeled by ideals, where the difference of two polynomials labeling adjacent vertices must belong to the corresponding ideal. The set of splines forms a ring. We consider spline rings where the underlying graph is the Cayley graph of a symmetric group generated by a collection of transpositions. These rings generalize the GKM construction for equivariant cohomology rings of flag, regular semisimple Hessenberg, and permutohedral varieties. These cohomology rings carry two actions of the symmetric group $S_n$ whose graded characters are both of general interest in algebraic combinatorics. In this paper, we generalize the graded $S_n$-representations from the cohomologies of the above varieties to splines on Cayley graphs of $S_n$, then (1) give explicit module and ring generators for whenever the $S_n$-generating set is minimal, (2) give a combinatorial characterization of when graded pieces of one $S_n$-representation is trivial, and (3) compute the first degree piece of both graded characters for all generating sets.
format Preprint
id arxiv_https___arxiv_org_abs_2401_14380
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Splines on Cayley Graphs of the Symmetric Group
Lesnevich, Nathan R. T.
Combinatorics
05E10 (Primary), 05C25, 20C30, 05E05 (Secondary)
A spline is an assignment of polynomials to the vertices of a graph whose edges are labeled by ideals, where the difference of two polynomials labeling adjacent vertices must belong to the corresponding ideal. The set of splines forms a ring. We consider spline rings where the underlying graph is the Cayley graph of a symmetric group generated by a collection of transpositions. These rings generalize the GKM construction for equivariant cohomology rings of flag, regular semisimple Hessenberg, and permutohedral varieties. These cohomology rings carry two actions of the symmetric group $S_n$ whose graded characters are both of general interest in algebraic combinatorics. In this paper, we generalize the graded $S_n$-representations from the cohomologies of the above varieties to splines on Cayley graphs of $S_n$, then (1) give explicit module and ring generators for whenever the $S_n$-generating set is minimal, (2) give a combinatorial characterization of when graded pieces of one $S_n$-representation is trivial, and (3) compute the first degree piece of both graded characters for all generating sets.
title Splines on Cayley Graphs of the Symmetric Group
topic Combinatorics
05E10 (Primary), 05C25, 20C30, 05E05 (Secondary)
url https://arxiv.org/abs/2401.14380