English

Tame topology over definable uniform structures

Logic 2021-10-15 v4

Abstract

A visceral structure on M is given by a definable base for a uniform topology on its universe in which all basic open sets are infinite and any infinite definable subset X of M has non-empty interior. This context includes o-minimal ordered groups, p-adic fields, and other examples. Assuming only viscerality, we show that the definable sets in M satisfy some desirable topological tameness conditions. For example, any definable unary function on M has a finite set of discontinuities; any definable function on a Cartesian power of M is continuous on a nonempty open set; and assuming definable finite choice, we obtain a cell decomposition result for definable sets. Under an additional topological assumption ("no space-filling functions"), we prove that the natural notion of topological dimension is invariant under definable bijections. These results generalize theorems proved by Simon and Walsberg, who assumed dp-minimality in addition to viscerality. In the final section, we construct new examples of visceral structures.

Keywords

Cite

@article{arxiv.1505.06455,
  title  = {Tame topology over definable uniform structures},
  author = {Alfred Dolich and John Goodrick},
  journal= {arXiv preprint arXiv:1505.06455},
  year   = {2021}
}

Comments

27 pages

R2 v1 2026-06-22T09:40:27.366Z