A class of 2 * 2 - matrix functions
Heinz Langer, Annemarie Luger · University of Zagreb University Computing Centre (SRCE) · 2000
Abstract. For a special class 2 2{matrix functions operator representations of (z) and b (z): = (z)1 by means of self-adjoint linear relations A and bA in a Krein space K are given. Since bA is a 2-dimensional peturbation of A, results of [LMM] imply that \\singularities of positive type " of remain singularities of positive type of b with the possible exception of isolated points which have a \\ nite negative index".