On invariant transformations of matrix dyads
If \(D_ n\) denotes the set of all distinct ``basic stones'' (dyads) of a matrix with n-complex entry, let T be, for any fixed element \(ab^*\) in \(D_ n\), the matrices satisfying \((Ta)(Tb)^*=ab^*\). Let \(J(ab^*)\) be the set of all T matrices and let \(\tilde T\) be an \(n\times n\) complex matrix for which \(\tilde T^*\tilde T=E\) and \(D_ n(\tilde T)\) the set of all \(ab^*\) of \(D_ n\) for which \((\tilde Ta)(\tilde Tb)^*=ab^*\). The paper gives several structure theorems for \((J(ab^*),\cdot)\) and \((D_ n(\tilde T),\cdot)\).
scientific article; zbMATH DE number 4208284