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Norms of Minimal Projections

Hermann König·Nicole Tomczak-Jaegermann
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Abstract

It is proved that the projection constants of two- and three-dimensional spaces are bounded by $4/3$ and $(1+\sqrt 5)/2$, respectively. These bounds are attained precisely by the spaces whose unit balls are the regular hexagon and dodecahedron. In fact, a general inequality for the projection constant of a real or complex $n$-dimensional space is obtained and the question of equality therein is discussed.

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Hermann König, Nicole Tomczak-Jaegermann. 1992-11-17. Norms of Minimal Projections. https://arxiv.org/abs/math/9211211

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