English

The ring of real-valued functions which are continuous on a dense cozero set

General Topology 2025-02-24 v1

Abstract

Let T(X)T''(X) and T(X)T'(X) denote the collections of all real-valued functions on XX which are continuous on a dense cozero set and on an open dense subset of XX respectively. T(X)T''(X) contains C(X)C(X) and forms a subring of T(X)T'(X) under pointwise addition and multiplication. We inquire when T(X)=C(X)T''(X)=C(X) and when T(X)=T(X)T''(X)=T'(X). We also ponder over the question when is T(X)T''(X) isomorphic to C(Y)C(Y) for some topological space YY. We investigate some algebraic properties of the ring, T(X)T''(X) for a Tychonoff space XX. We provide several characterisations of T(X)T''(X) as a Von-Neumann regular ring. We define nowhere almost PP-spaces using the ring T(X)T''(X) and characterise it as a Tychonoff space which has no non-isolated almost PP-points. We show that a Tychonoff space with countable pseudocharacter is a nowhere almost PP-space and highlight that this condition is not superflous using the closed ordinal space.

Keywords

Cite

@article{arxiv.2502.15358,
  title  = {The ring of real-valued functions which are continuous on a dense cozero set},
  author = {Amrita Dey and Sagarmoy Bag and Dhananjoy Mandal},
  journal= {arXiv preprint arXiv:2502.15358},
  year   = {2025}
}
R2 v1 2026-06-28T21:52:36.266Z