### Abstract

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 homeomorphism a of the real line that ensure the following: if b belongs 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 function b (x) is semi-Fredholm, then the Toeplitz operator with the matrix symbol b (a (x)) is also semi-Fredholm.

Original language | English (US) |
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Pages (from-to) | 2157-2176 |

Number of pages | 20 |

Journal | International Journal of Mathematics and Mathematical Sciences |

Volume | 2003 |

Issue number | 34 |

DOIs | |

State | Published - Jan 1 2003 |

### ASJC Scopus subject areas

- Mathematics (miscellaneous)

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## Cite this

Böttcher, A., Grudsky, S., & Spitkovsky, I. (2003). Block Toeplitz operators with frequency-modulated semi-almost periodic symbols.

*International Journal of Mathematics and Mathematical Sciences*,*2003*(34), 2157-2176. https://doi.org/10.1155/S0161171203107107