Abstract
In this paper a definition is given for an unbounded Toeplitzlike operator with rational symbol which has poles on the unit circle. It is shown that the operator is Fredholm if and only if the symbol has no zeroes on the unit circle, and a formula for the index is given as well. Finally, a matrix representation of the operator is discussed.
| Original language | English |
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| Title of host publication | Operator Theory, Analysis and the State Space Approach |
| Subtitle of host publication | In Honor of Rien Kaashoek |
| Editors | Harm Bart, Sanne ter Horst, André C.M. Ran, Hugo J. Woerdeman |
| Publisher | Birkhäuser |
| Pages | 239-268 |
| Number of pages | 30 |
| ISBN (Electronic) | 9783030042691 |
| ISBN (Print) | 9783030042684 |
| DOIs | |
| Publication status | Published - 2018 |
Publication series
| Name | Operator Theory: Advances and Applications |
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| Publisher | Birkhäuser |
| Volume | 271 |
| ISSN (Print) | 0255-0156 |
| ISSN (Electronic) | 2296-4878 |
Funding
This work is based on the research supported in part by the National Research Foundation of South Africa (Grant Number 90670 and 93406). Part of the research was done during a sabbatical of the third author, in which time several research visits to VU Amsterdam and North-West University were made. Support from University of Cape Town and the Department of Mathematics, VU Amsterdam is gratefully acknowledged. Acknowledgement. The present work is based on research supported in part by the National Research Foundation of South Africa. Any opinion, finding and conclusion or recommendation expressed in this material is that of the authors and the NRF does not accept any liability in this regard. The present work is based on research supported in part by the National Research Foundation of South Africa. Any opinion, finding and conclusion or recommendation expressed in this material is that of the authors and the NRF does not accept any liability in this regard. We would also like to thank the anonymous referee for the useful suggestions, corrections and comments.
| Funders | Funder number |
|---|---|
| National Research Foundation | |
| National Research Foundation of South Africa | 90670, 93406 |
| National Research Foundation |
Keywords
- Fredholm properties
- Toeplitz operators
- Unbounded operators