Pseudocompact topological groups and their properties.

*(English. Russian original)*Zbl 0712.22002
Sib. Math. J. 30, No. 1, 120-128 (1989); translation from Sib. Mat. Zh. 30, No. 1(173), 154-164 (1989).

A subspace X of a topological space Y is said to be bounded in Y if every continuous, real-valued function on Y is bounded on X. Using the elegant observation that a necessary and sufficient condition for boundedness of X in Y is that only finitely many elements of any locally finite family of sets open in Y can intersect X, it is shown that the cartesian product of an arbitrary family of bounded subsets of topological groups is bounded in the product of the groups. [This, of course, generalizes the well-known theorem of Comfort and Ross.] It is also shown that a continuous pseudometric on a topological group is uniformly continuous on any bounded subspace, as is any real-valued continuous function defined on G. Furthermore, the universal, two-sided, left and right uniformities from the group are equal on X. If G is algebraically generated by X and X is bounded, then any real-valued function on X can be factored through a continuous homomorphism onto a group of countable weight. A union of countably many bounded subspaces is said to be sigma-bounded. A (Tychonoff) space X is then sigma-bounded iff all of the following are also sigma-bounded: the free topological group on X, the free topological Abelian group on X, and the free linear locally convex space on X.

Reviewer: D.L.Grant

##### Keywords:

bounded subsets of topological groups; theorem of Comfort and Ross; continuous pseudometric; uniformly continuous; uniformities; sigma- bounded; free topological group; free linear locally convex space
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\textit{M. G. Tkachenko}, Sib. Math. J. 30, No. 1, 120--128 (1989; Zbl 0712.22002); translation from Sib. Mat. Zh. 30, No. 1(173), 154--164 (1989)

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##### References:

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