## Advances in Differential Equations

### Morse theory and a scalar field equation on compact surfaces

Andrea Malchiodi

#### Abstract

The aim of this paper is to study a nonlinear scalar field equation on a surface $\Sigma$ via a Morse-theoretical approach, based on some of the methods in [25]. Employing these ingredients, we derive an alternative and direct proof (plus a clear interpretation) of a degree formula obtained in [18], which used refined blow-up estimates from [34] and [17]. Related results are derived for the prescribed $Q$-curvature equation on four manifolds.

#### Article information

Source
Adv. Differential Equations, Volume 13, Number 11-12 (2008), 1109-1129.

Dates
First available in Project Euclid: 18 December 2012

Permanent link to this document
https://projecteuclid.org/euclid.ade/1355867288

Mathematical Reviews number (MathSciNet)
MR2483132

Zentralblatt MATH identifier
1175.53052

#### Citation

Malchiodi, Andrea. Morse theory and a scalar field equation on compact surfaces. Adv. Differential Equations 13 (2008), no. 11-12, 1109--1129. https://projecteuclid.org/euclid.ade/1355867288