English

On the bordification of outer space

Group Theory 2018-04-04 v2

Abstract

We give a simple construction of an equivariant deformation retract of Outer space which is homeomorphic to the Bestvina-Feighn bordification. This results in a much easier proof that the bordification is (2n-5)-connected at infinity, and hence that Out(Fn)Out(F_n) is a virtual duality group.

Cite

@article{arxiv.1709.01296,
  title  = {On the bordification of outer space},
  author = {Kai-Uwe Bux and Peter Smillie and Karen Vogtmann},
  journal= {arXiv preprint arXiv:1709.01296},
  year   = {2018}
}

Comments

Accepted version, to appear in the Journal of the London MS. Section 7, giving the homeomorphism to the Bestvina-Feighn bordification, has been substantially revised

R2 v1 2026-06-22T21:33:18.576Z