The elliptical range theorem for the conformal range

Gyula Lakos

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arXiv · 2603.23545

The elliptical range theorem for the conformal range

Gyula Lakos

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Abstract

The conformal range (or the real Davis--Wielandt shell), which is a particular planar projection of the Davis--Wielandt shell, can be considered as the hyperbolic version of the numerical range; i. e. it is a ``field of values'' which can be interpreted as a subset of the asymptotically closed hyperbolic plane. Here we explain the analogue of the elliptical range theorem of $2\times2$ complex matrices for the conformal range.

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Gyula Lakos. 2026-03-16. The elliptical range theorem for the conformal range. https://arxiv.org/abs/2603.23545

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