English

The classification of $C(K)$ spaces for countable compacta by positive isomorphisms

Functional Analysis 2026-01-19 v1

Abstract

We study the classification of spaces of continuous functions C(K)C(K) under positive linear maps. For infinite countable compacta, we show that whenever C(K)C(K) and C(L)C(L) are isomorphic, there exists an isomorphism T:C(K)C(L)T:C(K)\to C(L) satisfying either T0T\geq 0 or T10T^{-1}\geq 0. We also prove that for any compact spaces KK and LL, the existence of a positive embedding T:C(K)C(L)T: C(K) \to C(L) implies that the Cantor-Bendixson height of KK does not exceed the height of LL. Furthermore, we introduce a one-sided positive Banach-Mazur distance and obtain new estimates for both the classical and positive distances. Notably, we prove the exact formula dBM(C(ωωα),C(ωωαn))=n+(n1)(n+3)d_{BM}(C(\omega^{\omega^\alpha}), C(\omega^{\omega^\alpha n})) = n+\sqrt{(n-1)(n+3)}.

Keywords

Cite

@article{arxiv.2601.11463,
  title  = {The classification of $C(K)$ spaces for countable compacta by positive isomorphisms},
  author = {Marek Cúth and Jonáš Havelka and Jakub Rondoš and Bünyamin Sarı},
  journal= {arXiv preprint arXiv:2601.11463},
  year   = {2026}
}
R2 v1 2026-07-01T09:07:52.696Z