## Advances in Differential Equations

- Adv. Differential Equations
- Volume 11, Number 6 (2006), 627-646.

### Extended solutions for general fast diffusion equations with optimal measure data

Emmanuel Chasseigne and Juan Luis Vazquez

#### Abstract

We study the theory of existence and uniqueness of nonlinear diffusion equations of the form \[ u_{t}=\Delta \varphi(u)\quad\text{in}\quad\mathbb{R}^{N} \times(0,\infty), \] where $\varphi:{{\mathbb{R}^N}}_+\to{{\mathbb{R}^N}}_+$ is a continuous and increasing function. We focus on the fast diffusion type by imposing the growth condition : $$ \qquad {\displaystyle} m_1\le \dfrac{s\varphi'(s)}{\varphi(s)} \le m_2, $$ for some constants $0 < m_1\le m_2 < 1$ and all $s>0$. Moreover, $m_1>(N-2)/N$. Existence is obtained for an optimal class of initial data, namely, for any nonnegative Borel measure (not necessarily a locally finite measure). Uniqueness is proven for concave $\varphi$'s. The results extend to the general equation the optimal theory with measure-valued data now available for the equation with power functions $\varphi(s)=s^{m}$. The asymptotic behaviour is also studied.

#### Article information

**Source**

Adv. Differential Equations, Volume 11, Number 6 (2006), 627-646.

**Dates**

First available in Project Euclid: 18 December 2012

**Permanent link to this document**

https://projecteuclid.org/euclid.ade/1355867688

**Mathematical Reviews number (MathSciNet)**

MR2238022

**Zentralblatt MATH identifier**

1173.35561

**Subjects**

Primary: 35K55: Nonlinear parabolic equations

Secondary: 35K65: Degenerate parabolic equations

#### Citation

Chasseigne, Emmanuel; Vazquez, Juan Luis. Extended solutions for general fast diffusion equations with optimal measure data. Adv. Differential Equations 11 (2006), no. 6, 627--646. https://projecteuclid.org/euclid.ade/1355867688