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Countable dense homogeneous filters and the Menger covering property

Dušan Repovš, Lyubomyr Zdomskyy, Shuguo Zhang (2014)

Fundamenta Mathematicae

We present a ZFC construction of a non-meager filter which fails to be countable dense homogeneous. This answers a question of Hernández-Gutiérrez and Hrušák. The method of the proof also allows us to obtain for any n ∈ ω ∪ {∞} an n-dimensional metrizable Baire topological group which is strongly locally homogeneous but not countable dense homogeneous.

Embedding a topological group into a connected group

Ryo Ohashi (2007)

Colloquium Mathematicae

It was proved in [HM] that each topological group (G,·,τ) may be embedded into a connected topological group (Ĝ,•,τ̂). In fact, two methods of introducing τ̂ were given. In this note we show relations between them.

Equivalence of certain free topological groups

Jan Baars (1992)

Commentationes Mathematicae Universitatis Carolinae

In this paper we give a complete isomorphical classification of free topological groups F M ( X ) of locally compact zero-dimensional separable metric spaces X . From this classification we obtain for locally compact zero-dimensional separable metric spaces X and Y that the free topological groups F M ( X ) and F M ( Y ) are isomorphic if and only if C p ( X ) and C p ( Y ) are linearly homeomorphic.

Equivariant completions

Michael Megrelishvili (1994)

Commentationes Mathematicae Universitatis Carolinae

An important consequence of a result of Katětov and Morita states that every metrizable space is contained in a complete metrizable space of the same dimension. We give an equivariant version of this fact in the case of a locally compact σ -compact acting group.

Every reasonably sized matrix group is a subgroup of S ∞

Robert Kallman (2000)

Fundamenta Mathematicae

Every reasonably sized matrix group has an injective homomorphism into the group S of all bijections of the natural numbers. However, not every reasonably sized simple group has an injective homomorphism into S .

Extensions of topological and semitopological groups and the product operation

Aleksander V. Arhangel'skii, Miroslav Hušek (2001)

Commentationes Mathematicae Universitatis Carolinae

The main results concern commutativity of Hewitt-Nachbin realcompactification or Dieudonné completion with products of topological groups. It is shown that for every topological group G that is not Dieudonné complete one can find a Dieudonné complete group H such that the Dieudonné completion of G × H is not a topological group containing G × H as a subgroup. Using Korovin’s construction of G δ -dense orbits, we present some examples showing that some results on topological groups are not valid for semitopological...

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