English

The strong Pytkeev property in topological spaces

General Topology 2021-11-01 v1

Abstract

A topological space XX has the strong Pytkeev property at a point xXx\in X if there exists a countable family N\mathcal N of subsets of XX such that for each neighborhood OxXO_x\subset X and subset AXA\subset X accumulating at xx, there is a set NNN\in\mathcal N such that NOxN\subset O_x and NAN\cap A is infinite. We prove that for any 0\aleph_0-space XX and any space YY with the strong Pytkeev property at a point yYy\in Y the function space Ck(X,Y)C_k(X,Y) has the strong Pytkeev property at the constant function X{y}YX\to \{y\}\subset Y. If the space YY is rectifiable, then the function space Ck(X,Y)C_k(X,Y) is rectifiable and has the strong Pytkeev property at each point. We also prove that for any pointed spaces (Xn,n)(X_n,*_n), nωn\in\omega, with the strong Pytkeev property their Tychonoff product and their small box-product both have the strong Pytkeev property at the distinguished point. We prove that a sequential rectifiable space XX has the strong Pytkeev property if and only if XX is metrizable or contains a clopen submetrizable kωk_\omega-subspace. A locally precompact topological group is metrizable if and only if it contains a dense subgroup with the strong Pytkeev property.

Keywords

Cite

@article{arxiv.1412.4268,
  title  = {The strong Pytkeev property in topological spaces},
  author = {Taras Banakh and Arkady Leiderman},
  journal= {arXiv preprint arXiv:1412.4268},
  year   = {2021}
}

Comments

15 pages. arXiv admin note: text overlap with arXiv:1311.1468

R2 v1 2026-06-22T07:30:17.914Z