arXiv subjects
Publications and source records attributed to Huaiyu Jian.
We prove interior $C^{2}$ regularity result for convex viscosity solutions of the quadratic Hessian equation $σ_2(D^2u) = f(x)$, under the assumption that $f\in C^{0,1}$ with $\inf f>0$. The result is almost sharp: if $f$ are merely continuous, there exist convex viscosity solutions that fail to be $C^{1,1}$. When $f\in C^α$ for some $α\in (0,1)$, the corresponding interior regularity remains open.
We develop an integral approach to obtain interior a priori $C^{1,1}$ estimates for convex solutions of prescribing scalar curvature equations $σ_2(κ) = f(x)$ as well as the Hessian equations $σ_2(D^2u) = f(x)$. This new approach can deal with the case when $f$ is of weaker regularity. As a result, we prove that the $C^{1,1}$ modules of the solutions depend only on the Lipschitz modules of $f(x)$, instead of the $\|f\|_{C^k}$ for some $k\geq 2$ in all the papers we have known up to now.
We study the first derivative estimates for solutions to Monge-Ampère equations in terms of modulus of continuity. As a result, we establish the optimal global log-Lipschitz continuity for the gradient of solutions to the Monge-Ampère equation with natural boundary conditions.
In this paper, we investigate the strong maximum principle for generalized solutions of Monge-Ampère type equations. We prove that the strong maximum principle holds at points where the function is strictly convex but not necessarily $C^{1,1}$ smooth, and show that it fails at non-strictly convex points. The results we obtain can be applied to various Minkowski type problems in convex geometry by the virtue of the Gauss image map.
We study the good shape property of boundary sections of convex solutions of the oblique boundary value problem for Monge-Ampère equations $$\det D^2u =f(x) \text{ in } Ω, \quad D_βu = ϕ(x) \text{ on } \partial Ω.$$ In the two-dimensional case, we prove the global $C^{2,α}$ estimate for the solution. When the dimension $n \geq 3$, we show that this estimate still holds if the solution is bounded from above by a quadratic function in the tangent direction. We also obtain an existence result for the convex solution of Monge-Ampère equations with Robin oblique boundary conditions.
We study the exact effect of the anisotropic convexity of domains on the boundary estimate for two Monge-Ampère Equations: one is singular which is from the proper affine hyperspheres with constant mean curvature; the other is degenerate which is from the Monge-Ampère eigenvalue problem. As a result, we obtain the sharp boundary boundary estimates and the optimal global Hölder regularity for the two equations.
We derive rigorously the reduced dynamical laws for quantized vortex dynamics of the nonlinear Schrödinger equation on the torus with non-vanishing momentum when the vortex core size ε \to 0. The reduced dynamical laws are governed by a Hamiltonian flow driven by a renormalized energy. A key ingredient is to construct a new canonical harmonic map to include the effect from the non-vanishing momentum into the dynamics. Finally, some properties of the reduced dynamical law are discussed.
A number of geometric problems, including affine hyperbolic spheres, Hilbert metrics and Minkowski type problems, are reduced to a singular Monge-Ampère equation which can be written locally as a class of Monge-Ampère equations with singularity at boundary. We estimate the boundary derivatives of all orders for the solutions to the class of singular equations as possible as optimal and prove that the solution to the equation is globally analytic if the dimension of the space is even. As a corollary, we obtain the global analyticity of affine hyperbolic spheres in the even dimensional space.
We introduce the concept of k-strictly convexity to describe the accurate convexity of convex domains some directions of which boundary may be flat. Basing this accurate convexity, we construct sub-solutions the Dirichlet problem for some degenerate-singular Monge-Ampère type equations and prove the sharp boundary estimates for convex viscosity solutions of the problem. As a result, we obtain the optimal global Hölder regularity of the convex viscosity solutions.
In this paper, we study the Neumann problem of Monge-Ampère equations in Semi-space. For two dimensional case, we prove that its viscosity convex solutions must be a quadratic polynomial. When the space dimension $n\geq 3$, we show that the conclusion still holds if either the boundary value is zero or the viscosity convex solutions restricted on some $n-2$ dimensional subspace is bounded from above by a quadratic function.
In this paper we shall prove the existence, uniqueness and global H$\ddot{o}$lder continuity for the Dirichlet problem of a class of Monge-Ampère type equations which may be degenerate and singular on the boundary of convex domains. We will establish a relation of the H$\ddot{o}$lder exponent for the solutions with the convexity for the domains.
In this paper we study the global regularity for the solution to the Dirichlet problem of the equation of minimal graphs over a convex domain in hyperbolic spaces. We find that the global regularity depends only on the convexity of the domain but independent of its smoothness. Basing on the invariance of the problem under translation and rotation transforms, we construct the super-solution to the problem, by which we prove the optimal and accurate global regularity for this problem.
In this paper, we study the convexity, interior gradient estimate, Liouville type theorem and asymptotic behavior at infinity of translating solutions to mean curvature flow as well as the nonlinear flow by powers of the mean curvature.
In this paper, we study the evolution of submannifold moving by mean curvature minus a external force field. We prove that the flow has a long-time smooth solution for all time under almost optimal conditions. Those conditions are that the second fundamental form on the initial submanifolds is not too large, the external force field, with its any order derivatives, is bounded, and the field is convex with its eigenvalues satisfying a pinch inequality.
In this paper, we study the Hessian equation with infinite Dirichlet (blow-up) boundary value conditions. Using radial functions and techniques of ordinary differential inequality, we construct various barrier functions (super-solution and sub-solution). Existence and non-existence theorems are proved by those barriers, maximum principle and theory of viscous solutions. Furthermore, generic boundary blow-up rates for the solutions are derived.
In this paper, we study the existence, uniqueness and asymptotic behavior of rotationally symmetric translating solitons of the mean curvature flow in Minkowski space. We also study the asymptotic behavior and the strict convexity of general solitons of such flows.
We are concerned with spacelike convex hypersurfaces of positive constant (K-hypersurfaces) or prescribed Gauss curvature in Minkowski space. Our main purpose is to study entire solutions as well as the Dirichlet problem in bounded domains of the related Monge-Ampere equation.
Consider the anisotropic porous medium equation, $u_t=\sum\limits_{i=1}^n(u^{m_i})_{x_ix_i},$ where $m_i>0, (i=1,2,...,n)$ satisfying $\min\limits_{1\le i\le n}\{m_i\}\le 1,$ $\sum\limits_{i=1}^nm_i>n-2,$ and $\max\limits_{1\le i\le n}\{m_i\}\le \frac{1}{n}(2+\sum\limits_{i=1}^nm_i).$ Assuming that the initial data belong only to $L^1(\Re^n)$, we establish the existence and uniqueness of the solution for the Cauchy problem in the space, $C([0,\infty), L^1(\Re^n))\cap C(\Re^n\times(0,\infty))\cap L^\infty(\Re^n\times[ε,\infty)),$ where $ε>0$ may be arbitrary. We also show a comparison principle for such solutions. Furthermore, we prove that the solution converges to zero in the space $L^\infty(\Re^n)$ as the time goes to infinity.