Algebras of block Toeplitz matrices with commuting entries

Abstract

The maximal algebras of scalar Toeplitz matrices are known to be formed by generalized circulants. The identification of algebras consisting of block Toeplitz matrices is a harder problem, that has received little attention up to now. We consider the case when the block entries of the matrices belong to a commutative algebra $\mathcal{A}$. After obtaining some general results, we classify all the maximal algebras for certain particular cases of $\mathcal{A}$.