**SMS scnews item created by Daniel Daners at Thu 8 Oct 2009 0940**

Type: Seminar

Distribution: World

Expiry: 12 Oct 2009

**Calendar1: 12 Oct 2009 1500-1600**

**CalLoc1: Carslaw 454**

Auth: daners@p7153.pc.maths.usyd.edu.au

### PDE Seminar

# Existence and non-existence of solutions for a class of Monge-Ampère equations

### Zhang

Zhitao Zhang

Academy of Mathematics and Systems Sciences, The
Chinese Academy of Sciences, Beijing

12 Oct 2009 3-4pm, Carslaw Room 454

## Abstract

We study the boundary value problems for a class of
Monge-Ampère equations: det D^{2}u = e^{-u} in Ω ⊂ R^{n},n ≥ 1, u|_{
∂Ω} = 0. First we
prove that any solution on the ball is radially symmetric by the argument of
moving plane. Then we reduce the equation to an ODE, and show there exists a
critical radius such that if the radius of a ball is smaller than this critical value,
then there exists a solution and vice versa. Using the comparison between
domains we can prove that this phenomenon occurs for every domain. We
calculate the one dimensional case explicitly, which also indicates some kind of
bifurcation phenomena may exist. Finally for the fixed domain we consider an
equivalent problem with a parameter det D^{2}u = e^{-tu} in Ω, u|_{
∂Ω} = 0,t ≥ 0. By
using Lyapunov-Schmidt Reduction method we get the local structure of the
solutions near a degenerate point; by Leray-Schauder degree theory, a
priori estimates and bifurcation theory we get the global structure and
prove existence of at least two solutions for a certain range of parameters
t (0,T^{*}), a unique solution at t = T^{*}, nonexistence of solution for t > T^{*}.

Check also the PDE Seminar page. Enquiries to Florica Cîrstea or Daniel Daners.