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Automatic continuity and $C_0(\Omega)$-linearity of linear maps between $C_0(\Omega)$-modules
- Publication Year :
- 2010
-
Abstract
- Let $\Omega$ be a locally compact Hausdorff space. We show that any local $\mathbb{C}$-linear map (where "local" is a weaker notion than $C_0(\Omega)$-linearity) between Banach $C_0(\Omega)$-modules are "nearly $C_0(\Omega)$-linear" and "nearly bounded". As an application, a local $\mathbb{C}$-linear map $\theta$ between Hilbert $C_0(\Omega)$-modules is automatically $C_0(\Omega)$-linear. If, in addition, $\Omega$ contains no isolated point, then any $C_0(\Omega)$-linear map between Hilbert $C_0(\Omega)$-modules is automatically bounded. Another application is that if a sequence of maps $\{\theta_n\}$ between two Banach spaces "preserve $c_0$-sequences" (or "preserve ultra-$c_0$-sequences"), then $\theta_n$ is bounded for large enough $n$ and they have a common bound. Moreover, we will show that if $\theta$ is a bijective "biseparating" linear map from a "full" essential Banach $C_0(\Omega)$-module $E$ into a "full" Hilbert $C_0(\Delta)$-module $F$ (where $\Delta$ is another locally compact Hausdorff space), then $\theta$ is "nearly bounded" (in fact, it is automatically bounded if $\Delta$ or $\Omega$ contains no isolated point) and there exists a homeomorphism $\sigma: \Delta \rightarrow \Omega$ such that $\theta(e\cdot \varphi) = \theta(e)\cdot \varphi\circ \sigma$ ($e\in E, \varphi\in C_0(\Omega)$).
Details
- Database :
- arXiv
- Publication Type :
- Report
- Accession number :
- edsarx.1005.4561
- Document Type :
- Working Paper