English

Algebraic and o-minimal flows beyond the cocompact case

Algebraic Geometry 2022-09-23 v1 Logic

Abstract

Let XCnX \subset \mathbb{C}^n be an algebraic variety, and let ΛCn\Lambda \subset \mathbb{C}^n be a discrete subgroup whose real and complex spans agree. We describe the topological closure of the image of XX in Cn/Λ\mathbb{C}^n / \Lambda, thereby extending a result of Peterzil-Starchenko in the case when Λ\Lambda is cocompact. We also obtain a similar extension when XRnX\subset \mathbb{R}^n is definable in an o-minimal structure with no restrictions on Λ\Lambda, and as an application prove the following conjecture of Gallinaro: for a closed semi-algebraic XCnX\subset \mathbb{C}^n (such as a complex algebraic variety) and exp:Cn(C)n\exp:\mathbb{C}^n\to (\mathbb{C}^*)^n the coordinate-wise exponential map, we have exp(X)=exp(X)i=1mexp(Ci)Ti\overline{\exp(X)}=\exp(X)\cup \bigcup_{i=1}^m \exp(C_i)\cdot \mathbb{T}_i where Ti(C)n\mathbb{T}_i\subset (\mathbb{C}^*)^n are positive-dimensional compact real tori and CiCnC_i\subset \mathbb{C}^n are semi-algebraic.

Keywords

Cite

@article{arxiv.2209.10812,
  title  = {Algebraic and o-minimal flows beyond the cocompact case},
  author = {Spencer Dembner and Hunter Spink},
  journal= {arXiv preprint arXiv:2209.10812},
  year   = {2022}
}

Comments

8 pages, comments welcome!

R2 v1 2026-06-28T01:52:28.859Z