4 papers
On Periodic Matrix-Valued Weyl-Titchmarsh Functions
M. Bekker, E. Tsekanovskii
We consider a certain class of Herglotz-Nevanlinna matrix-valued functions which can be realized as the Weyl-Titchmarsh matrix-valued function of some symmetric operator and its se…
Some Applications of Operator-Valued Herglotz Functions
Fritz Gesztesy, Nigel J. Kalton, Konstantin A. Makarov +1
We consider operator-valued Herglotz functions and their applications to self-adjoint perturbations of self-adjoint operators and self-adjoint extensions of densely defined closed…
On Matrix-Valued Herglotz Functions
Fritz Gesztesy, Eduard Tsekanovskii
We provide a comprehensive analysis of matrix-valued Herglotz functions and illustrate their applications in the spectral theory of self-adjoint Hamiltonian systems including matri…
An Addendum to Krein's Formula
Fritz Gesztesy, Konstantin A. Makarov, Eduard Tsekanovskii
We provide additional results in connection with Krein's formula, which describes the resolvent difference of two self-adjoint extensions A_1 and A_2 of a densely defined closed sy…