This is an announcement for the paper "Minimal projections with respect to numerical radius" by Asuman G. Aksoy and Grzegorz Lewicki.

Abstract: In this paper we survey some results on minimality of projections with respect to numerical radius. We note that in the cases $L^p$, $p=1,2,\infty$, there is no difference between the minimality of projections measured either with respect to operator norm or with respect to numerical radius. However, we give an example of a projection from $l^p_3$ onto a two-dimensional subspace which is minimal with respect to norm, but not with respect to numerical radius for $p\neq 1,2,\infty$. Furthermore, utilizing a theorem of Rudin and motivated by Fourier projections, we give a criterion for minimal projections, measured in numerical radius. Additionally, some results concerning strong unicity of minimal projections with respect to numerical radius are given.

Archive classification: math.FA

Mathematics Subject Classification: Primary 41A35, 41A65, Secondary 47A12

Remarks: 15 pages

Submitted from: aaksoy@cmc.edu

The paper may be downloaded from the archive by web browser from URL

http://front.math.ucdavis.edu/1402.0032

or

http://arXiv.org/abs/1402.0032