https://neckpinch.com/authors/fei-yang/New arXiv papers by Fei Yang, from Neckpinch Tue, 10 Nov 2026 04:10:28 GMT https://neckpinch.com/papers/1707.04846/arxiv:1707.04846Sun, 16 Jul 2017 00:00:00 GMTFei Yang, Liangdi Zhang — In this paper, we prove some classification results for four-dimensional gradient Ricci solitons. For a four-dimensional gradient shrinking Ricci soliton with div⁴Rm^±=0, we show that it is either Einstein or a finite quotient of ℝ⁴, S²×ℝ² or S³×ℝ. The same result can be obtained under the condition of div⁴W^±=0. We also present some classification results of four-dimensional complete non-compact gradient expanding Ricci soliton with non-negative Ricci curvature and gradient steady Ricci solitons under certain curvature conditions.Ricci solitons4-manifoldsBoundaries & non-compact https://neckpinch.com/papers/1705.09754/arxiv:1705.09754Sat, 27 May 2017 00:00:00 GMTFei Yang, Liangdi Zhang — We prove that a gradient shrinking Ricci soliton with fourth order divergence-free Riemannian tensor is rigid. For the 4-dimensional case, we show that any gradient shrinking Ricci soliton with fourth order divergence-free Riemannian tensor is either Einstein, or a finite quotient of the Gaussian shrinking soliton ℝ⁴, ℝ²×S² or the round cylinder ℝ×S³. Under the condition of fourth order divergence-free Weyl tensor, we have the same results.Ricci solitonsStability & uniqueness