On the ideal structure of the tensor product of nearly simple algebras

Abstract

We define a unital algebra $A$ over a field $\mathbb{F}$ to be nearly simple if $A$ contains a unique non-trivial ideal $I_A$ such that $I_A^2\ne \{0\}$. If $A$ and $B$ are two nearly simple algebras, we consider the ideal structure of their tensor product $A\otimes B$. The obvious non-trivial ideals of $A\otimes B$ are: $$I_A \otimes I_B, \quad I_A \otimes B, \quad A \otimes I_B, \quad \mbox{and} \quad I_A \otimes B + A \otimes I_B.$$ The purpose of this paper is to characterize when are all non-trivial ideals of $A\otimes B$ of the above form.

11 pages, to appear in Comm. Algebra