On the automorphism of Barns Wall Lattice $\Lambda_{BW_{16}}$ and rank 4 tensor of quaternions

TL;DR

This paper explores the automorphism group of the Barns Wall Lattice BW_{16} by extending quaternion tensor products to rank 4, revealing a new algebraic construction linked to Hurwitz quaternions.

Contribution

It introduces a novel algebraic construction of the automorphism group of BW_{16} using rank 4 tensor products of Hurwitz quaternions, extending previous quaternion tensor work.

Findings

Constructed an algebra isomorphic to Aut(BW_{16})

Extended quaternion tensor rank from 2 to 4

Identified the automorphism group's order and structure

Abstract

In a previous paper, I found that the Weyl group $W(F_4)$ and Barns-Wall Lattice $BW_{16}$ can be constructed using the rank $2$ tensor of the quaternion. In the present paper, I describe how I were able to construct an algebra, which is the subalgebra of the direct product of Hurwitz Quaternionic integers $\mathscr{H}^4$, isomorphic to the automorphism $\text{Aut}(BW_{16})$ order $2^{21} \cdot 3^5 \cdot 5^2 \cdot 7$ of Barns Wall Lattice $BW_{16}$ by functionally extending the rank of the tensor product of quaternions to $4$.