Factorization of matrix functions with subgroup supported Fourier coefficients ✩

It is proved that if a Wiener class matrix function on a connected compact abelian group admits a factorization with respect to a connected compact abelian supergroup, then it admits a factorization with respect to the original group. In particular, all factorization indices are characters of the original group. An illustrative example is considered. © 2005 Elsevier Inc. All rights reserved