Zobrazeno 1 - 10
of 576
pro vyhledávání: '"Mill Jan"'
Autor:
Juhász, István, van Mill, Jan
Answering a question raised by V. V. Tkachuk, we present several examples of $\sigma$-compact spaces, some only consistent and some in ZFC, that are not countably tight but in which the closure of any discrete subset is countably tight. In fact, in s
Externí odkaz:
http://arxiv.org/abs/2411.04523
We show that in the class of Lindel\"of \v{C}ech-complete spaces the property of being $C$-embedded is quite well-behaved. It admits a useful characterization that can be used to show that products and perfect preimages of $C$-embedded spaces are aga
Externí odkaz:
http://arxiv.org/abs/2404.19703
Sets on the boundary of a complementary component of a continuum in the plane have been of interest since the early 1920's. Curry and Mayer defined the buried points of a plane continuum to be the points in the continuum which were not on the boundar
Externí odkaz:
http://arxiv.org/abs/2401.10206
Autor:
Juhász, István, van Mill, Jan
If $X$ is a topological space and $Y$ is any set then we call a family $\mathcal{F}$ of maps from $X$ to $Y$ nowhere constant if for every non-empty open set $U$ in $X$ there is $f \in \mathcal{F}$ with $|f[U]| > 1$, i.e. $f$ is not constant on $U$.
Externí odkaz:
http://arxiv.org/abs/2312.12257
Autor:
Juhász, István, van Mill, Jan
We show that every infinite crowded space can be mapped onto a homogeneous space of countable weight, and that there is a homogeneous space of weight continuum that cannot be mapped onto a homogeneous space of uncountable weight strictly less than co
Externí odkaz:
http://arxiv.org/abs/2310.20359
We provide partial solutions to two problems posed by Shehtman concerning the modal logic of the \v{C}ech-Stone compactification of an ordinal space. We use the Continuum Hypothesis to give a finite axiomatization of the modal logic of $\beta(\omega^
Externí odkaz:
http://arxiv.org/abs/2308.13684
We investigate closed copies of~$\mathbb{N}$ in powers of~$\mathbb{R}$ with respect to $C^*$- and $C$-embedding. We show that $\mathbb{R}^{\omega_1}$ contains closed copies of~$\mathbb{N}$ that are not $C^*$-embedded.
Comment: Version 2: some co
Comment: Version 2: some co
Externí odkaz:
http://arxiv.org/abs/2307.07223
Autor:
Juhász, István, Van Mill, Jan
The set $dd(X)$ of densities of all dense subspaces of a topological space $X$ is called the double density spectrum of $X$. In this note we present a couple of results that imply $\lambda \in dd(X)$, provided that $X$ is a compact space and $\lambda
Externí odkaz:
http://arxiv.org/abs/2302.02348
Publikováno v:
Topology Proceedings 62 (2023), 205-216 (e-published on 25-08-2023)
We present examples of realcompact spaces with closed subsets that are C*-embedded but not C-embedded, including one where the closed set is a copy of the space of natural numbers.
Comment: Version 2: corrections after referee report. One questi
Comment: Version 2: corrections after referee report. One questi
Externí odkaz:
http://arxiv.org/abs/2211.16545
Autor:
Hart, Klaas Pieter, van Mill, Jan
Publikováno v:
Topology and its Applications 2024
This is an update on, and expansion of, our paper Open problems on $\beta\omega$ in the book Open Problems in Topology.
Comment: New version, much reworked. 2024-02-01: version after comments from the referee. 2024-08-24: added classification, k
Comment: New version, much reworked. 2024-02-01: version after comments from the referee. 2024-08-24: added classification, k
Externí odkaz:
http://arxiv.org/abs/2205.11204