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Matthias Ludewig
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Tensors and Nuclear/Fredholm Operators

For a locally convex Hausdorff spaces $E$, consider the canonical map $$\overline{\psi}:E^\prime \hat{\otimes}_\pi E \longrightarrow L(E_\sigma)$$ that maps the projective tensor product to the space of weakly continuous maps on $E$ (note that if $E$ is Banach spaces, then the latter is just the space $L(E)$ of bounded linear operators).

The question whether this map is injective is well-known to be connected to the approximation property. For example:

  • If $E$ is a Banach space, then $E$ has the approximation property if and only if $\overline{\psi}$ is injective.

  • If $E$ has is a complete locally convex space with a fundamental system of absolutely convex neighborhoods $U$ of zero such that every Banach space $E_U$ has the approximation property, then $\hat{\psi}$ is one-to-one.

These statements can be found in Köthe's book "Topologcial Vector Spaces II$.

Question: If $E$ is complete and has the approximation property, is it false/true/not known whether $\hat{\psi}$ is injective in general?

Matthias Ludewig
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