English

Enumeration degrees and non-metrizable topology

General Topology 2020-09-18 v2 Logic in Computer Science Logic

Abstract

The enumeration degrees of sets of natural numbers can be identified with the degrees of difficulty of enumerating neighborhood bases of points in a universal second-countable T0T_0-space (e.g. the ω\omega-power of the Sierpi\'nski space). Hence, every represented second-countable T0T_0-space determines a collection of enumeration degrees. For instance, Cantor space captures the total degrees, and the Hilbert cube captures the continuous degrees by definition. Based on these observations, we utilize general topology (particularly non-metrizable topology) to establish a classification theory of enumeration degrees of sets of natural numbers.

Keywords

Cite

@article{arxiv.1904.04107,
  title  = {Enumeration degrees and non-metrizable topology},
  author = {Takayuki Kihara and Keng Meng Ng and Arno Pauly},
  journal= {arXiv preprint arXiv:1904.04107},
  year   = {2020}
}
R2 v1 2026-06-23T08:32:59.791Z