Stadler, Stephan Max Planck Institute for Mathematics, Max Planck Society;
https://doi.org/10.48550/arXiv.2109.09438 (Preprint)
2109.09438.pdf (Preprint), 681KB
Lytchak, A., Nagano, K., & Stadler, S. (in press). CAT(0) 4-manifolds are Euclidean. Geometry & Topology, Accepted for publication.