English

Compactness and Connectedness in Aura Topological Spaces

General Topology 2026-02-10 v1

Abstract

This is the second paper in a series on aura topological spaces (X,τ,a)(X, \tau, \mathfrak{a}), where a:Xτ\mathfrak{a}: X \to \tau is a scope function with xa(x)x \in \mathfrak{a}(x). We study covering and connectivity properties in this setting. Five compactness-type notions are defined (a\mathfrak{a}-compact, a\mathfrak{a}-Lindelof, countably a\mathfrak{a}-compact, a\mathfrak{a}-sequentially compact, a\mathfrak{a}-limit point compact) and their mutual relationships are determined. For transitive aura functions we obtain a concrete convergence criterion: (xn)(x_n) converges to xx in τa\tau_{\mathfrak{a}} if and only if xna(x)x_n \in \mathfrak{a}(x) eventually. We show that a\mathfrak{a}-compact subsets of a\mathfrak{a}-T2T_2 spaces are a\mathfrak{a}-closed and that a\mathfrak{a}-compactness is preserved under a\mathfrak{a}-continuous surjections. On the connectivity side, a\mathfrak{a}-connected, a\mathfrak{a}-path connected, and a\mathfrak{a}-locally connected spaces are introduced; a\mathfrak{a}-components are a\mathfrak{a}-closed, and they are a\mathfrak{a}-open when the space is a\mathfrak{a}-locally connected. We construct subspace and product aura topologies. For products the inclusion chain (τa)×(τb)τa×bτX×τY(\tau_{\mathfrak{a}}) \times (\tau_{\mathfrak{b}}) \subseteq \tau_{\mathfrak{a} \times \mathfrak{b}} \subseteq \tau_X \times \tau_Y is established, with equality on the left when both scope functions are transitive. A Tychonoff-type theorem for transitive aura spaces is proved. All implications are shown to be strict by counterexamples.

Keywords

Cite

@article{arxiv.2602.07686,
  title  = {Compactness and Connectedness in Aura Topological Spaces},
  author = {Ahu Acikgoz},
  journal= {arXiv preprint arXiv:2602.07686},
  year   = {2026}
}

Comments

17 pages. Second paper in the Aura Topological Spaces series

R2 v1 2026-07-01T10:26:15.068Z