Short proofs of the fact that the limit space of a non-gauged approximate system of non-empty compact uniform spaces is non-empty and of two related results are given.

Let $X$ be a continuum. In Proposition 31 of J.J. Charatonik and W.J. Charatonik, Smoothness and the property of Kelley, Comment. Math. Univ. Carolin. 41 (2000), no. 1, 123–132, it is claimed that $L\left(X\right)={\bigcap }_{p\in X}S\left(p\right)$, where $L\left(X\right)$ is the set of points at which $X$ is locally connected and, for $p\in X$, $a\in S\left(p\right)$ if and only if $X$ is smooth at $p$ with respect to $a$. In this paper we show that such equality is incorrect and that the correct equality is $P\left(X\right)={\bigcap }_{p\in X}S\left(p\right)$, where $P\left(X\right)$ is the set of points at which $X$ is connected im kleinen. We also use the correct...

In a series of papers, Bandt and the author have given a symbolic and topological description of locally connected quadratic Julia sets by use of special closed equivalence relations on the circle called Julia equivalences. These equivalence relations reflect the landing behaviour of external rays in the case of local connectivity, and do not apply completely if a Julia set is connected but fails to be locally connected. However, rational external rays land also in the general case. The present...

In this note we first give a summary that on property of a remainder of a non-locally compact topological group $G$ in a compactification $bG$ makes the remainder and the topological group $G$ all separable and metrizable. If a non-locally compact topological group $G$ has a compactification $bG$ such that the remainder $bG\setminus G$ of $G$ belongs to $𝒫$, then $G$ and $bG\setminus G$ are separable and metrizable, where $𝒫$ is a class of spaces which satisfies the following conditions: (1) if $X\in 𝒫$, then every compact subset of the space $X$ is a...

$Z$-continuous posets are common generalizations of continuous posets, completely distributive lattices, and unique factorization posets. Though the algebraic properties of $Z$-continuous posets had been studied by several authors, the topological properties are rather unknown. In this short note an intrinsic topology on a $Z$-continuous poset is defined and its properties are explored.

We present the original proof, based on the Doitchinov completion, that a totally bounded quiet quasi-uniformity is a uniformity. The proof was obtained about ten years ago, but never published. In the mean-time several stronger results have been obtained by more direct arguments [8, 9, 10]. In particular it follows from Künzi’s [8] proofs that each totally bounded locally quiet quasi-uniform space is uniform, and recently Déak [10] observed that even each totally bounded Cauchy quasi-uniformity...

In this note, we show that if for any transitive neighborhood assignment $\phi$ for $X$ there is a point-countable refinement $ℱ$ such that for any non-closed subset $A$ of $X$ there is some $V\in ℱ$ such that $|V\cap A|\ge \omega$, then $X$ is transitively $D$. As a corollary, if $X$ is a sequential space and has a point-countable $wc{s}^{*}$-network then $X$ is transitively $D$, and hence if $X$ is a Hausdorff $k$-space and has a point-countable $k$-network, then $X$ is transitively $D$. We prove that if $X$ is a countably compact sequential space and has a point-countable...

Using Tsirelson’s well-known example of a Banach space which does not contain a copy of $c_0$ or $l_p$, for p ≥ 1, we construct a simple Borel ideal $I_T$ such that the Borel cardinalities of the quotient spaces $P\left(\mathbb{N}\right)/I_T$ and $P\left(\mathbb{N}\right)/I_0$ are incomparable, where $I_0$ is the summable ideal of all sets A ⊆ ℕ such that ${\sum }_{n\in A}1/(n+1)<\infty$. This disproves a “trichotomy” conjecture for Borel ideals proposed by Kechris and Mazur.