Year: 2026
Type: preprint
Abstract: This note gives direct proofs that, under an effective isometric $T^2$ action, Einstein metrics on smooth homotopy four-spheres are round and complete Ricci-flat metrics on smooth manifolds homeomorphic to $\mathbb R^4$ are Euclidean or positive one-center Taub--NUT, up to isometry, scaling, and orientation reversal.
Source: arXiv (Cornell University)
Authors: Chen, Xiuxiong, Dong, Conghan
Language: English
Subfield: Geometry and Topology
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221188954
