Graphs, Axial Algebras and their Automorphism Groups

TL;DR

This paper introduces a new class of algebras linked to directed graphs with labeled edges, characterizes their properties, and demonstrates how to construct simple axial algebras with prescribed automorphism groups.

Contribution

It defines a novel class of graph-related algebras, determines their fusion laws and automorphism groups, and provides a method to construct simple axial algebras with any given automorphism group.

Findings

Algebras are simple in most cases.

Automorphism groups depend on graph properties.

Construction method for algebras with any automorphism group.

Abstract

We introduce a class of algebras over a field $\mathbb{F}$ related to directed graphs in which all edges are labeled by nonzero elements of the field $\mathbb{F}$. If all labels are different from $1$, these algebras are axial algebras. We determine their fusion laws, prove them to be simple in almost all cases, and determine their automorphism group under some conditions on the degrees and girth of the graph. A construction of a class of these graphs with prescribed automorphism group enables us to construct for each group $G$ infinitely many simple (axial) algebras (with a fixed fusion law) such that the automorphism group of the algebra is isomorphic to $G$.