The classification of torsion-free abelian groups of finite rank up to isomorphism and up to quasi-isomorphism

This post is a link to https://arxiv.org/abs/0902.1218

Transactions of the American mathematical society 364:175–194.

Abstract: The isomorphism and quasi-isomorphism relations on the $p$-local torsion-free abelian groups of rank $n\geq3$ are incomparable with respect to Borel reducibility.