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arXiv · 2601.12923

On Kippenhahn curves of low rank partial isometries

Nikita Popov·Eric Shen·Ilya M. Spitkovsky
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Abstract

Conditions are established for rank three partial isometries to have circular components contained in their Kippenhahn curves. In particular, such matrices with circular numerical ranges are described. It is also established that the Gau-Wang-Wu conjecture holds for matrices under consideration.

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Nikita Popov, Eric Shen, Ilya M. Spitkovsky. 2026-01-19. On Kippenhahn curves of low rank partial isometries. https://doi.org/10.1007/s00020-026-02846-w

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