2021/06/25 by Leiderman, Arkady, Uspenskij, Vladimir
#54D30 #FOS: Mathematics #Functional Analysis (math.FA) #General Topology (math.GN) #Primary 46A03 #Secondary 46B25
paper · doi:10.48550/arxiv.2106.13413
Given a class \mathcal P of Banach spaces, a locally convex space (LCS) E is called \em multi-\mathcal P if E can be isomorphically embedded into a product of spaces that belong to \mathcal P. We investigate the question whether the free locally convex space L(X) is strongly nuclear, nuclear, Schwartz, multi-Hilbert or multi-reflexive. If X is a Tychonoff space containing an infinite compact subset then, as it follows from the results of \citeAus, L(X) is not nuclear. We prove that for such X the free LCS L(X) has the stronger property of not being multi-Hilbert. We deduce that if X is a k-space, then the following properties are equivalent: (1) L(X) is strongly nuclear; (2) L(X) is nuclear; (3) L(X) is multi-Hilbert; (4) X is countable and discrete. On the other hand, we show that L(X) is strongly nuclear for every projectively countable P-space (in particular, for every Lindelöf P-space) X. We observe that every Schwartz LCS is multi-reflexive. It is known that if X is a kω-space, then L(X) is a Schwartz LCS \citeChasco, hence L(X) is multi-reflexive. We show that for any first-countable paracompact (in particular, metrizable) space X the converse is true, so L(X) is multi-reflexive if and only if X is a kω-space, equivalently, if X is a locally compact and σ-compact space. Similarly, we show that for any first-countable paracompact space X the free abelian topological group A(X) is a Schwartz group if and only if X is a locally compact space such that the set X(1) of all non-isolated points of X is σ-compact.