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On extreme contractions and vertices in operator spaces

Karol Gryszka, Paweł Wójcik Colloquium Mathematicum MSC: Primary 46B20; Secondary 46B25, 46A32 DOI: 10.4064/cm9442-3-2025 Published online: 12 May 2025

Abstract

The investigations of the extreme points of the closed unit ball in spaces of operators were started by Kadison (1954) considering the operator space $\mathcal L(H)$. Grząślewicz (1997) considered the vertices of subsets of $\mathcal L(H)$. In this paper, motivated by more recent results, we investigate the extreme points and vertices in $\mathcal L(\ell _{\infty }^n,\ell _{1}^m)$, $\mathcal L(c_0,\ell _{1})$ and $\mathcal L(\ell _{1})$.

Authors

  • Karol GryszkaInstitute of Mathematics
    University of the National Education Commission
    30-084 Kraków, Poland
    e-mail
  • Paweł WójcikInstitute of Mathematics
    University of the National Education Commission
    30-084 Kraków, Poland
    e-mail

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