Sufficiently collapsed irreducible Alexandrov 3-spaces are geometric

Abstract

We prove that sufficiently collapsed, closed and irreducible three-dimensional Alexandrov spaces are modeled on one of the eight three-dimensional Thurston geometries. This extends a result of Shioya and Yamaguchi, originally formulated for Riemannian manifolds, to the Alexandrov setting.

We have added a proof of the fact that a closed collapsing Alexandrov 3-space cannot admit hyperbolic geometry (see Remark B). This improves our main Theorem (Theorem A) by ruling out the appearance of hyperbolic geometry. 24 pages, 3 Tables