The Dirichlet problem for fully nonlinear elliptic equations on Riemannian manifolds

We solve the Dirichlet problem for fully nonlinear elliptic equations on Riemannian manifolds under essentially optimal structure conditions, especially with no restrictions to the curvature of the underlying manifold and the second fundamental form of its boundary. The main result (Theorem 1.1) includes a new (and optimal) result in the Euclidean case. We introduce some new ideas and methods in deriving a priori estimates, which can be used to treat other types of fully nonlinear elliptic and parabolic equations on real or complex manifolds

Second Order Estimates and Regularity for Fully Nonlinear Elliptic Equations on Riemannian Manifolds

We derive a priori second order estimates for solutions of a class of fully nonlinear elliptic equations on Riemannian manifolds under some very general structure conditions. We treat both equations on closed manifolds, and the Dirichlet problem on manifolds with boundary without any geometric restrictions to the boundary except being smooth and compact. As applications of these estimates we obtain results on regularity and existence

A Monge-Ampere Type Fully Nonlinear Equation on Hermitian Manifolds

We study a fully nonlinear equation of complex Monge-Ampere type on Hermitian manifolds. We establish the a priori estimates for solutions of the equation up to the second order derivatives with the help of a subsolution

On a class of fully nonlinear elliptic equations on Hermitian manifolds

We derive a priori $C^2$ estimates for a class of complex Monge-Ampere type equations on Hermitian manifolds. As an application we solve the Dirichlet problem for these equations under the assumption of existence of a subsolution; the existence result, as well as the second order boundary estimates, is new even for bounded domains in \bfC^n

Hypersurfaces of constant curvature in Hyperbolic space

We show that for a very general and natural class of curvature functions, the problem of finding a complete strictly convex hypersurface satisfying f({\kappa}) = {\sigma} over (0,1) with a prescribed asymptotic boundary {\Gamma} at infinity has at least one solution which is a "vertical graph" over the interior (or the exterior) of {\Gamma}. There is uniqueness for a certain subclass of these curvature functions and as {\sigma} varies between 0 and 1, these hypersurfaces foliate the two components of the complement of the hyperbolic convex hull of {\Gamma}

The Dirichlet Problem for a Complex Monge-Ampere Type Equation on Hermitian Manifolds

We are concerned with fully nonlinear elliptic equations on complex manifolds and search for technical tools to overcome difficulties in deriving a priori estimates which arise due to the nontrivial torsion and curvature, as well as the general (non-pseudoconvex) shape of the boundary. We present our methods, which work for more general equations, by considering a specific equation which resembles the complex Monge-Ampere equation in many ways but with crucial differences. Our work is motivated by recent increasing interests in fully nonlinear equations on complex manifolds from geometric problems.Comment: Revised version based on the referees' reports, we would like to thank them for their helpful comment

Complex Monge-Ampere equations and totally real submanifolds

We study the Dirichlet problem for complex Monge-Ampere equations in Hermitian manifolds with general (non-pseudoconvex) boundary. Our main result extends the classical theorem of Caffarelli, Kohn, Nirenberg and Spruck in the flat case. We also consider the equation on compact manifolds without boundary, attempting to generalize Yau's theorems in the Kaehler case. As applications of the main result we study some connections between the homogeneous complex Monge-Ampere ({\em HCMA}) equation and totally real submanifolds, and a special Dirichlet problem for the HCMA equation related to Donaldson's conjecture on geodesics in the space of Kaehler metrics

Second order estimates for Hessian type fully nonlinear elliptic equations on Riemannian manifolds

We derive a priori estimates for second order derivatives of solutions to a wide calss of fully nonlinear elliptic equations on Riemannian manifolds. The equations we consider naturally appear in geometric problems and other applications such as optimal transportation. There are some fundamental assumptions in the literature to ensure the equations to be elliptic and that one can apply Evans-Krylov theorem once estimates up to second derivatives are derived. However, in previous work one needed extra assumptions which are more technical in nature to overcome various difficulties. In this paper we are able to remove most of these technical assumptions. Indeed, we derive the estimates under conditions which are almost optimal, and prove existence results for the Dirichlet problem which are new even for bounded domains in Euclidean space. Moreover, our methods can be applied to other types of nonlinear elliptic and parabolic equations, including those on complex manifolds

Maximally symmetric subspace decomposition of the Schwarzschild black hole

The well-known Schwarzschild black hole was first obtained as a stationary, spherically symmetric solution of the Einstein's vacuum field equations. But until thirty years later, efforts were made for the analytic extension from the exterior area $(r>2GM)$ to the interior one $(r<2GM)$. As a contrast to its maximally extension in the Kruskal coordinates, we provide a comoving coordinate system from the view of the observers freely falling into the black hole in the radial direction. We find an interesting fact that the spatial part in this coordinate system is maximally symmetric $(E_3)$, i.e., along the world lines of these observers, the Schwarzschild black hole can be decomposed into a family of maximally symmetric subspaces.Comment: Plain LaTex2e File, 8 pages, 1 eps figur

Statistical properties of radiation fields in a compact space

We discuss radiation fields in a compact space of finite size instead of that in a cavity for investigating the coupled atom-radiation field system. Representations of $T(1)\times SO(4)$ group are used to give a formulation for kinematics of the radiation fields. The explicit geometrical parameter dependence of statistical properties of radiation fields is obtained. Results show remarkable differences from that of the black-body radiation system in free space.Comment: LaTeX2e plain file of 10 pages, 1 eps figur