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5. Functional Analysis, Operator Theory and Operator Algebras, Mathematical Physics

On some classes of operators on $C(K, X)$

Ioana Ghenciu
University of Wisconsin-River Falls, USA

Abstract:

Suppose $X$ and $Y$ are Banach spaces, $K$ is a compact Hausdorff space, $\Sigma$ is the $\sigma$-algebra of Borel subsets of $K$, $C(K,X)$ is the Banach space of all continuous $X$-valued functions (with the supremum norm), and $T:C(K,X)\to Y$ is a strongly bounded operator with representing measure $m:\Sigma \to L(X,Y)$.

We show that if $T$ is a strongly bounded operator and $\hat{T}: B(K, X) \to Y$ is its extension, then $T$ is limited if and only if its extension $\hat{T}$ is limited and that $T^*$ is completely continuous (resp. unconditionally converging) if and only if $\hat{T}^*$ is completely continuous (resp. unconditionally converging).

We prove that if $K$ is a dispersed compact Hausdorff space and $T$ is a strongly bounded operator, then $T$ is limited (weakly precompact, has a completely continuous, resp. unconditionally converging adjoint) whenever $m(A):X\to Y$ is limited (weakly precompact, has a completely continuous, resp. unconditionally converging adjoint), for each $A \in \Sigma$.