• Medientyp: E-Artikel
  • Titel: Finitary approximations of coarse structures
  • Beteiligte: Protasov, I. V.
  • Erschienen: Ivan Franko National University of Lviv, 2021
  • Erschienen in: Matematychni Studii
  • Sprache: Nicht zu entscheiden
  • DOI: 10.30970/ms.55.1.33-36
  • ISSN: 2411-0620; 1027-4634
  • Schlagwörter: General Mathematics
  • Entstehung:
  • Anmerkungen:
  • Beschreibung: <jats:p>A coarse structure $ \mathcal{E}$ on a set $X$ is called finitary if, for each entourage $E\in \mathcal{E}$, there exists a natural number $n$ such that $ E[x]&lt; n $ for each $x\in X$. By a finitary approximation of a coarse structure $ \mathcal{E}^\prime$, we mean any finitary coarse structure $ \mathcal{E}$ such that $ \mathcal{E}\subseteq \mathcal{E}^\prime$.If $\mathcal{E}^\prime$ has a countable base and $E[x]$ is finite for each $x\in X$ then $ \mathcal{E}^\prime$has a cellular finitary approximation $ \mathcal{E}$ such that the relations of linkness on subsets of $( X,\mathcal{E}^\prime)$ and $( X, \mathcal{E})$ coincide.This answers Question 6 from [8]: the class of cellular coarse spaces is not stable under linkness. We define and apply the strongest finitary approximation of a coarse structure.</jats:p>
  • Zugangsstatus: Freier Zugang