Toeplitz Operators Defined by Piecewise Continuous Matrix Functions

Author(s):  
I. Gohberg ◽  
M. A. Kaashoek ◽  
S. Goldberg
2003 ◽  
Vol 2003 (34) ◽  
pp. 2157-2176 ◽  
Author(s):  
A. Böttcher ◽  
S. Grudsky ◽  
I. Spitkovsky

This paper is concerned with the influence of frequency modulation on the semi-Fredholm properties of Toeplitz operators with oscillating matrix symbols. The main results give conditions on an orientation-preserving homeomorphismαof the real line that ensure the following: ifbbelongs to a certain class of oscillating matrix functions (periodic, almost periodic, or semi-almost periodic matrix functions) and the Toeplitz operator generated by the matrix functionb(x)is semi-Fredholm, then the Toeplitz operator with the matrix symbolb(α(x))is also semi-Fredholm.


2020 ◽  
Vol 76 (1) ◽  
Author(s):  
M. C. Câmara ◽  
M. T. Malheiro ◽  
J. R. Partington

AbstractWe consider kernels of unbounded Toeplitz operators in $$H^p({\mathbb {C}}^{+})$$ H p ( C + ) in terms of a factorization of their symbols. We study the existence of a minimal Toeplitz kernel containing a given function in $$H^p({\mathbb {C}}^{+})$$ H p ( C + ) , we describe the kernels of Toeplitz operators whose symbol possesses a certain factorization involving two different Hardy spaces and we establish relations between the kernels of two operators whose symbols differ by a factor which corresponds, in the unit circle, to a non-integer power of z. We apply the results to describe the kernels of Toeplitz operators with non-vanishing piecewise continuous symbols.


2019 ◽  
Vol 57 (2) ◽  
pp. 429-435
Author(s):  
Santeri Miihkinen ◽  
Jani Virtanen

Author(s):  
I. Gohberg ◽  
M. A. Kaashoek ◽  
S. Goldberg

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