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Gabor frames, operator algebras, and quasicrystals

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About the project

In signal processing, periodic signals can be studied using Fourier series, where the basic building blocks are sine waves. However, when a signal changes substantially over time, such as a piece of music, different methods are needed. Gabor frames provide one such method. A Gabor frame allows for representations of a signal that emphasizes its frequency content at each point in time, similarly to how sheet music is written. When constructing a Gabor frame, a point set in the time-frequency plane needs to be specified. Gabor frames over lattice point sets enjoy a deep duality theory with connections to operator algebras and the representation theory of groups. For non-lattice point sets, these connections are less clear. The aim of this project is to fill this gap in the existing knowledge, associating operator algebras to Gabor frames over a class of point sets known as quasicrystals. In particular, a major goal is to prove existence results for Gabor frames over quasicrystals which generalize known results for lattices.

Financing

This project is financed by the Reseach Council of Norway. Funding ID: 314048

Publications

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  • Enstad, Ulrik Bo Rufus (2023). A dynamical approach to density theorems for sampling in unimodular groups.
  • Enstad, Ulrik Bo Rufus (2023). Density theorems for coherent systems via point set groupoids.
  • Enstad, Ulrik Bo Rufus (2023). Linear independence of coherent systems over lattices.
  • Enstad, Ulrik Bo Rufus (2023). Complete Gabor (and other coherent) systems over approximate lattices.
  • Enstad, Ulrik Bo Rufus (2022). Sufficient density conditions for coherent systems arising from discrete series representations.
  • Enstad, Ulrik Bo Rufus (2022). On sufficient conditions for lattice orbits of relative discrete series.
  • Enstad, Ulrik Bo Rufus (2022). Irregular sampling via groupoids associated to Delone sets.
  • Enstad, Ulrik Bo Rufus (2022). Gabor frames over approximate lattices.
  • Enstad, Ulrik Bo Rufus (2022). Reproducing properties of lattice orbits of nilpotent Lie groups.
  • Enstad, Ulrik Bo Rufus (2022). A dynamical approach to sampling and interpolation in unimodular groups.
  • Enstad, Ulrik Bo Rufus (2021). Frames generated by unitary representations of nilpotent Lie groups.

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Published Nov. 2, 2023 8:04 PM - Last modified Nov. 2, 2023 8:08 PM