English

Engel groups and universal surgery models

Geometric Topology 2021-09-30 v1

Abstract

We introduce a collection of 1/2-π1\pi_1-null 4-dimensional surgery problems. This is an intermediate notion between the classically studied universal surgery models and the π1\pi_1-null kernels which are known to admit a solution in the topological category. Using geometric applications of the group-theoretic 2-Engel relation, we show that the 1/2-π1\pi_1-null surgery problems are universal, in the sense that solving them is equivalent to establishing 4-dimensional topological surgery for all fundamental groups. As another application of these methods, we formulate a weaker version of the π1\pi_1-null disk lemma and show that it is sufficient for proofs of topological surgery and s-cobordism theorems for good groups.

Keywords

Cite

@article{arxiv.1707.07800,
  title  = {Engel groups and universal surgery models},
  author = {Michael Freedman and Vyacheslav Krushkal},
  journal= {arXiv preprint arXiv:1707.07800},
  year   = {2021}
}
R2 v1 2026-06-22T20:56:20.909Z