A. Ravsky

activity

20162026

most citedLinear Geometry: flats, ranks, regularity, parallelity

1 citations · 2 across the 13 of their papers we have counts for

collaborators

Showing 2020Show all

7 papers · 1 filter

math.GN2020

On unconditionally convergent series in topological rings

Taras Banakh, Alex Ravsky

We define a topological ring $R$ to be \emph{Hirsch}, if for any unconditionally convergent series $\sum_{n \in ω} x_{i}$ in $R$ and any neighborhood $U$ of the additive identity $0$ o…

math.GN2020

Suitable sets for paratopological groups

Fucai Lin, Alex Ravsky, Tingting Shi

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 $⟨ S ⟩$ of $…

math.FA2020

A note on approximation of continuous functions on normed spaces

M. A. Mytrofanov, A. V. Ravsky

Let $X$ be a real separable normed space $X$ admitting a separating polynomial. We prove that each continuous function from a subset $A$ of $X$ to a real Banach space can be unifor…

math.GN2020

A countably compact topological group with the non-countably pracompact square

Serhii Bardyla, Alex Ravsky, Lyubomyr Zdomskyy

Under Martin's Axiom we construct a Boolean countably compact topological group whose square is not countably pracompact.

math.GN2020

Each topological group embeds into a duoseparable topological group

Taras Banakh, Igor Guran, Alex Ravsky

A topological group $X$ is called $d u ose p a r ab l e$ if there exists a countable set $S \subseteq X$ such that $S U S = X$ for any neighborhood $U \subseteq X$ of the unit. We construct a fu…

cs.DM2020

The Complexity of Finding Tangles

Oksana Firman, Philipp Kindermann, Boris Klemz +3

We study the following combinatorial problem. Given a set of $n$ y-monotone curves, which we call wires, a tangle determines the order of the wires on a number of horizontal layers…