Zobrazeno 1 - 10
of 33
pro vyhledávání: '"Alex Ravsky"'
Publikováno v:
Pracì Mìžnarodnogo Geometričnogo Centru, Vol 13, Iss 3, Pp 10-17 (2020)
We construct a metrizable Lawson semitopological semilattice $X$ whose partial order $\le_X\,=\{(x,y)\in X\times X:xy=x\}$ is not closed in $X\times X$. This resolves a problem posed earlier by the authors.
Externí odkaz:
https://doaj.org/article/357e999c7a014805831e981eac8f132b
Autor:
Serhii Bardyla, Alex Ravsky
Publikováno v:
Applied General Topology, Vol 21, Iss 2, Pp 201-214 (2020)
We investigate closed subsets (subsemigroups, resp.) of compact-like topological spaces (semigroups, resp.). We show that each Hausdorff topological space is a closed subspace of some Hausdorff ω-bounded pracompact topological space and describe ope
Externí odkaz:
https://doaj.org/article/48c5fbd1b8c345e5bcf0e4f95fce25a8
Publikováno v:
Applied General Topology, Vol 12, Iss 1, Pp 27-33 (2011)
We prove that a Hausdorff paratopological group G is meager if andonly if there are a nowhere dense subset A G and a countable setC G such that CA = G = AC.
Externí odkaz:
https://doaj.org/article/35f6db6b0375441cb3bb3654947c5c4b
Publikováno v:
Topological Algebra and its Applications, Vol 8, Iss 1, Pp 76-87 (2020)
A topological semigroup is monothetic provided it contains a dense cyclic subsemigroup. The Koch problem asks whether every locally compact monothetic monoid is compact. This problem was opened for more than sixty years, till in 2018 Zelenyuk obtaine
Publikováno v:
Journal of Graph Algorithms and Applications. 23:371-391
Given a drawing of a graph, its \emph{visual complexity} is defined as the number of geometrical entities in the drawing, for example, the number of segments in a straight-line drawing or the number of arcs in a circular-arc drawing (in 2D). Recently
A paratopological group $G$ has a {\it suitable set} $S$. The latter means that $S$ is a discrete subspace of $G$, $S\cup \{e\}$ is closed, and the subgroup $\langle S\rangle$ of $G$ generated by $S$ is dense in $G$. Suitable sets in topological grou
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::26d66a646b11fba6c95e2e46252e6b36
http://arxiv.org/abs/2005.08233
http://arxiv.org/abs/2005.08233
A topological group $X$ is called $duoseparable$ if there exists a countable set $S\subseteq X$ such that $SUS=X$ for any neighborhood $U\subseteq X$ of the unit. We construct a functor $F$ assigning to each (abelian) topological group $X$ a duosepar
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::92b27c2f2e4232c2d56d6611ca055a0d
http://arxiv.org/abs/2002.06232
http://arxiv.org/abs/2002.06232
Publikováno v:
Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales. Serie A. Matemáticas. 114
Given a Tychonoff space $X$, let $F(X)$ and $A(X)$ be respectively the free topological group and the free Abelian topological group over $X$ in the sense of Markov. In this paper, we consider two topological properties of $F(X)$ or $A(X)$, namely th
We discuss various modifications of separability, precompactnmess and narrowness in topological groups and test those modifications in the permutation groups $S(X)$ and $S_{
Comment: 6 pages
Comment: 6 pages
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2135e12716b6d5b847b4a73560778a52
Autor:
Taras Banakh, Markiyan Simkiv, Alex Ravsky, Ostap Chervak, Tetyana Martynyuk, Maksym Pylypovych
Publikováno v:
Topological Algebra and its Applications, Vol 6, Iss 1, Pp 1-25 (2018)
Generalizing the famous 14-set closure-complement Theorem of Kuratowski from 1922, we prove that for a set $X$ endowed with $n$ pairwise comparable topologies $\tau_1\subset\dots\subset\tau_n$, by repeated application of the operations of complement