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arXiv · 2606.02922

From Clouatre-Ostermann-Ransford to Okubo-Ando

Michael Hartz·John E. McCarthy
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Abstract

We prove that if $\theta$ is a continuous unital homomorphism of an operator algebra $A$ into $B(\mathcal{H})$, and $\beta$ is in the dual space of $A$, then the completely bounded norm of $\theta$ is less than or equal to the maximum of $1$ and the completely bounded norm of $\theta + \beta I $. As an application, we give another proof of the Okubo--Ando theorem.

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Michael Hartz, John E. McCarthy. 2026-06-01. From Clouatre-Ostermann-Ransford to Okubo-Ando. https://arxiv.org/abs/2606.02922

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