Arithmetical Structures on Bidents

Document Type

Article

Publication Date

7-2020

Department 1

Mathematics

Abstract

An arithmetical structure on a finite, connected graph G is a pair of vectors (d,r) with positive integer entries for which (diag(d)−A)r=0, where A is the adjacency matrix of G and where the entries of r have no common factor. The critical group of an arithmetical structure is the torsion part of the cokernel of (diag(d)−A). In this paper, we study arithmetical structures and their critical groups on bidents, which are graphs consisting of a path with two “prongs” at one end. We give a process for determining the number of arithmetical structures on the bident with n vertices and show that this number grows at the same rate as the Catalan numbers as n increases. We also completely characterize the groups that occur as critical groups of arithmetical structures on bidents.

DOI

10.1016/j.disc.2020.111850

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