English

Topological properties of some function spaces

General Topology 2020-04-14 v1

Abstract

Let YY be a metrizable space containing at least two points, and let XX be a YIY_{\mathcal{I}}-Tychonoff space for some ideal I\mathcal{I} of compact sets of XX. Denote by CI(X,Y)C_{\mathcal{I}}(X,Y) the space of continuous functions from XX to YY endowed with the I\mathcal{I}-open topology. We prove that CI(X,Y)C_{\mathcal{I}}(X,Y) is Fr\'{e}chet - Urysohn iff XX has the property γI\gamma_{\mathcal{I}}. We characterize zero - dimensional Tychonoff spaces XX for which the space CI(X,2)C_{\mathcal{I}}(X,{\bf 2}) is sequential. Extending the classical theorems of Gerlits, Nagy and Pytkeev we show that if YY is not compact, then Cp(X,Y)C_{p}(X,Y) is Fr\'{e}chet - Urysohn iff it is sequential iff it is a kk-space iff XX has the property γ\gamma. An analogous result is obtained for the space of bounded continuous functions taking values in a metrizable locally convex space. Denote by B1(X,Y)B_{1}(X,Y) and B(X,Y)B(X,Y) the space of Baire one functions and the space of all Baire functions from XX to YY, respectively. If HH is a subspace of B(X,Y)B(X,Y) containing B1(X,Y)B_{1}(X,Y), then HH is metrizable iff it is a σ\sigma - space iff it has countable cscs^* - character iff XX is countable. If additionally YY is not compact, then HH is Fr\'{e}chet - Urysohn iff it is sequential iff it is a kk - space iff it has countable tightness iff X0X_{\aleph_0} has the property γ\gamma, where X0X_{\aleph_0} is the space XX with the Baire topology. We show that if XX is a Polish space, then the space B1(X,R)B_{1}(X,\mathbb{R}) is normal iff XX is countable.

Keywords

Cite

@article{arxiv.2004.05321,
  title  = {Topological properties of some function spaces},
  author = {Saak Gabriyelyan and Alexander V. Osipov},
  journal= {arXiv preprint arXiv:2004.05321},
  year   = {2020}
}

Comments

39 pages

R2 v1 2026-06-23T14:47:46.540Z