English

Computable categoricity relative to a c.e. degree

Logic 2025-05-08 v2

Abstract

A computable graph G\mathcal{G} is computably categorical relative to a degree d\mathbf{d} if and only if for all d\mathbf{d}-computable copies B\mathcal{B} of G\mathcal{G}, there is a d\mathbf{d}-computable isomorphism f:GBf:\mathcal{G}\to\mathcal{B}. In this paper, we prove that for every computable partially ordered set PP and computable partition P=P0P1P=P_0\sqcup P_1, there exists a computable computably categorical graph G\mathcal{G} and an embedding hh of PP into the c.e. degrees where G\mathcal{G} is computably categorical relative to all degrees in h(P0)h(P_0) and not computably categorical relative to any degree in h(P1)h(P_1). This is a generalization of a 2021 result by Downey, Harrison-Trainor, and Melnikov.

Keywords

Cite

@article{arxiv.2401.06641,
  title  = {Computable categoricity relative to a c.e. degree},
  author = {Java Darleen Villano},
  journal= {arXiv preprint arXiv:2401.06641},
  year   = {2025}
}

Comments

21 pages

R2 v1 2026-06-28T14:15:21.316Z