Enclosing a Compact Set in an O-minimal Expansion of $(\mathbb{R},+,\cdot,0,1 <)$
Logic
2026-07-27 v1
Abstract
Fix an o-minimal expansion R=(R,+,⋅,0,1<,...) of the real ordered field. Given C1 functions f1,...,fk, g1,...,gk:M→R on a definable cell M, let hi,0 denote fi and hi,1 denote gi. Suppose that for all τ∈2[k], Hτ=(h1,τ(1),..,hk,τ(k)):M→Rk is regular and proper on M, and that for all i∈[k], {fi=0} and {gi=0} are connected, and {fi=0}∩{gi=0}=∅. We show that then there exists a sequence (□i,ϵ:i∈[k],ϵ∈{0,1})∈{≤,≥}[k]×{0,1} such that the enclosed region i∈[k]⋂{fi□i,00}∩{gi□i,10} is compact.
Cite
@article{arxiv.2607.24627,
title = {Enclosing a Compact Set in an O-minimal Expansion of $(\mathbb{R},+,\cdot,0,1 <)$},
author = {Yayi Fu},
journal= {arXiv preprint arXiv:2607.24627},
year = {2026}
}