Glasnik matematički, Vol. 35 No. 1, 2000.
Original scientific paper
A class of 2 * 2 - matrix functions
Heinz Langer
Annemarie Luger
Abstract
For a special class 2 × 2-matrix functions Ω operator representations of Ω(z) and Ω^(z) := - Ω(z) -1 by means of self-adjoint linear relations A and A^ in a Krein space K are given. Since A^ is a 2-dimensional perturbation of A, results of Langer, Markus and Matsaev imply that "singularities of positive type" of Ω remain singularities of positive type of Ω^ with the possible exception of isolated points which have a "finite negative index".
Keywords
Hrčak ID:
4867
URI
Publication date:
1.6.2000.
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