Intersection of subspaces in $A^2$ for a three-dimensional division algebra $A$ over a finite field

Abstract

Let $A$ be a three-dimensional nonassociative division algebra over a finite field. Let $A$ act on the space $A^2$ by left multiplication. For a nonzero vector $v$ in $A^2$ we have a three-dimensional subspace $Av$ in $A^2$. This paper concerns about possible dimension of the intersection of $Av$ and $A{v}^{\prime }$ for $v,v^{\prime }$ in $A^2$. One of our results is that there exists a two-dimensional intersection if and only if $A$ is isotopic to a commutative algebra. We use a classical theorem that A is a twisted field of Albert.

27 pages