## Advances in Differential Equations

- Adv. Differential Equations
- Volume 14, Number 9/10 (2009), 963-984.

### Curves of equiharmonic solutions and ranges of nonlinear equations

#### Abstract

We consider the semilinear Dirichlet problem \[ \Delta u+kg(u)=\mu _1 {\varphi} _1+\ldots +\mu _n {\varphi} _n+e(x) \; \; \mbox{for $x \in U$}, \; \; u=0 \; \; \mbox{on $\partial U$}, \] where ${\varphi} _k$ is the $k$-th eigenfunction of the Laplacian on $U$ and $e(x) \perp {\varphi} _k$, $k=1, \ldots,n$. We write the solution in the form $u(x)= \sum _{i=1}^n \xi _i {\varphi} _i+U_{\xi } (x)$, with $ U_{\xi } \perp {\varphi} _k$, $k=1, \ldots,n$. Starting with $k=0$, when the problem is linear, we continue the solution in $k$ by keeping $\xi =(\xi _1, \ldots,\xi _n)$ fixed, but allowing $\mu =(\mu _1, \ldots,\mu _n)$ to vary. We then study the map $\xi \rightarrow \mu$, which provides existence and multiplicity results for the above problem.

#### Article information

**Source**

Adv. Differential Equations, Volume 14, Number 9/10 (2009), 963-984.

**Dates**

First available in Project Euclid: 18 December 2012

**Permanent link to this document**

https://projecteuclid.org/euclid.ade/1355863336

**Mathematical Reviews number (MathSciNet)**

MR2548284

**Zentralblatt MATH identifier**

1185.35095

**Subjects**

Primary: 35J60: Nonlinear elliptic equations

#### Citation

Korman, Philip. Curves of equiharmonic solutions and ranges of nonlinear equations. Adv. Differential Equations 14 (2009), no. 9/10, 963--984. https://projecteuclid.org/euclid.ade/1355863336