7 citations · 12 across the 4 of their papers we have counts for
4 papers
On questions of Pogorelov and Toponogov
Lei Ni, Wei Zhang, Yijian Zhang
We give explicit counterexamples to two questions. One is asked by Pogorelov and the other is by Toponogov. These questions concern the existence of closed asymptotic curves in a s…
Universality of the Divergence
Lei Ni, Yijian Zhang
Algebraists asked whether or not an operator on the module of smooth sections of the tangent bundle over the commutative ring of smooth functions of a smooth (orientable) manifold…
Four-dimentional Gradient Shrinking Solitons with Positive Isotropic Curvature
Xiaolong Li, Lei Ni, Kui Wang
We show that a four-dimensional complete gradient shrinking Ricci soliton with positive isotropic curvature is either a quotient of S^4 or a quotient of S^3 cross R. This gives a c…
Ancient solutions of Ricci flow on spheres and generalized Hopf fibrations
Ioannis Bakas, Shengli Kong, Lei Ni
Ancient solutions arise in the study of Ricci flow singularities. Motivated by the work of Fateev on 3-dimensional ancient solutions we construct high dimensional ancient solutions…