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JOURNALS // Fundamentalnaya i Prikladnaya Matematika // Archive

Fundam. Prikl. Mat., 2018 Volume 22, Issue 1, Pages 3–11 (Mi fpm1778)

This article is cited in 1 paper

Bounded contractibility of strict suns in three-dimensional spaces

A. R. Alimovab

a Faculty of Mechanics and Mathematics, Moscow State University, Moscow, Russia
b Steklov Mathematical Institute of Russian Academy of Sciences, Moscow, Russia

Abstract: A strict sun in a finite-dimensional (asymmetric) normed space $X$, $\operatorname {dim}X \le 3$, is shown to be $P$-contractible, $P$-solar, $\mathring B $-infinitely connected, $\mathring B $-contractible, $\mathring B $-retract, and having a continuous additive (multiplicative) $\varepsilon$-selection for any $\varepsilon > 0$. A $P$-acyclic subset of a three-dimensional space is shown to have a continuous $\varepsilon$-selection for any $\varepsilon > 0$. For the dimension $3$ the well-known Tsar'kov's characterization of spaces, in which any bounded Chebyshev set is convex, is extended to the case of strict suns.

UDC: 517.982.256+517.982.252


 English version:
Journal of Mathematical Sciences (New York), 2020, 250:3, 385–390

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© Steklov Math. Inst. of RAS, 2026