On reduction of block matrices in a Hilbert space

• Date: 2009
• Main Authors: Omel’chenko, P. V., Омельченко, П. В.
• Format: Article
• Language: Ukrainian; English
• Published: Institute of Mathematics, NAS of Ukraine 2009
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/3105
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

We study the problem of the reduction of self-adjoint block matrices $B = (B_ij)$ with given graph by a group of unitary block diagonal matrices. Under the condition that the matrices $B^2$ and $B^4$ are orthoscalar, we describe the graphs of block matrices for which this problem is a problem of *-f...