We show that a rescale limit at any degenerate singularity of Ricci flow in dimension 3 is a steady gradient soliton. In particular, we give a geometric description of type I and type II singularities.

A gradient Ricci soliton is a triple (M, g, f) satisfying Rij +∇i∇jf = λgij for some real number λ. In this paper, we will show that the completeness of the metric g implies that of the vector field ∇f .

We show that gradient shrinking, expanding or steady Ricci solitons have potentials leading to suitable reference probability measures on the manifold. For shrinking solitons, as well as expanding soltions with nonnegative Ricci curvature, these reference measures satisfy sharp logarithmic Sobolev inequalities with lower bounds characterized by the geometry of the manifold. The geometric invari...

Abstract. Given a family of biholomorphisms φt on a noncompact complex manifold M , we provide conditions, on φt, under which M is biholomorphic to C. As an application, we generalize previous results in [1]. We prove that if (M, g) is a complete non-compact gradient Kähler-Ricci soliton with potential function f which is either steady with positive Ricci curvature so that the scalar curvature ...

Following work of Ecker (Comm Anal Geom 15:1025–1061, 2007), we consider a weighted Gibbons-Hawking-York functional on a Riemannian manifold-withboundary. We compute its variational properties and its time derivative under Perelman’s modified Ricci flow. The answer has a boundary term which involves an extension of Hamilton’s differential Harnack expression for the mean curvature flow in Euclid...

We consider the Ricci flow for simply connected nilmanifolds, which translates to a Ricci flow on the space of nilpotent metric Lie algebras. We consider the evolution of the inner product with respect to time and the evolution of structure constants with respect to time, as well as the evolution of these quantities modulo rescaling. We set up systems of O.D.E.’s for some of these flows and des...

This is a short note explaining how one can compute the Gaussian density of the Kähler-Ricci soliton and the conformally Kähler, Einstein metric on the two point blow-up of the complex projective plane.

Let M be a real hypersurface of complex space form n ( c ) $M^n(c)$ , ≠ 0 $c\ne 0$ . Suppose that the structure vector field ξ is an eigen Ricci tensor S, S = β $S\xi =\beta \xi$ being function. We study on M, gradient pseudo-Ricci soliton g f λ μ $M,g,f,\lambda ,\mu$ extended concept soliton, closely related to pseudo-Einstein hypersurfaces. When ≥ 3 $n\ge 3$ we show Hopf hypersurface.