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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. LOMI, 1979 Volume 92, Pages 307–311 (Mi znsl3212)

This article is cited in 1 paper

Short communications

On the coincidence of two crossnorms connected with the order

V. T. Khudalov


Abstract: Let $E$ be an ordered normed space and $X$ be an arbitrary normed space. The following two crossnorms are considered: for
\begin{gather*} n_E(z)=\inf\biggl\{\|u\|:\sum_{k=1}^ne_k\langle x_k,x^*\rangle\le u,\ z=\sum_{k=1}^ne_k\otimes x_k,\ x^*\in X,\ \|x^*\|\le1\biggr\}, \\ k_E(z)=\inf\biggl\{\biggl\|\sum_{k=1}^ne_k\|x_k\|\biggr\|:z=\sum_{k=1}^ne_n\otimes x_k,\ e_k\ge0\biggr\}. \end{gather*}

Theorem 1. The following conditions are equivalent:
1) for every normed space $X$ and every $z\in E\otimes X$ we have $n_E(z)=k_E(z)$.
2) $E$ has the Riesz interpolation property
.

UDC: 517.972.1



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