English

An effective version of the Stone duality

Logic 2026-04-07 v1

Abstract

The paper studies computability-theoretic aspects of topological T0T_0-spaces. We introduce effective versions of the notions of a countable cc-poset and a (second-countable) topological space with base. Based on this, we prove an effective version of the known Stone-type duality between the category AS\mathbf{AS} (whose objects are almost semispectral spaces with base and whose morphisms are spectral mappings) and the category DP\mathbf{DP} (whose objects are distributive cc-posets and whose morphisms are strict mappings). Namely, we show that for an arbitrary set ZωZ\subseteq \omega, this duality is preserved when one restricts to objects which have ZZ-computably enumerable presentations only. Following this approach, we establish several results in computable topology. We prove that every degree spectrum of a countable algebraic structure can be realized as the degree spectrum of a topological space with base. We show that for any non-zero natural number NN, there is a computable topological space with base that has precisely NN-many computable copies, up to effective spectral homeomorphisms.

Keywords

Cite

@article{arxiv.2604.04492,
  title  = {An effective version of the Stone duality},
  author = {Nikolay A. Bazhenov and Iskander Sh. Kalimullin and Marina V. Schwidefsky},
  journal= {arXiv preprint arXiv:2604.04492},
  year   = {2026}
}

Comments

18 pages

R2 v1 2026-07-01T11:55:02.561Z