## Differential and Integral Equations

- Differential Integral Equations
- Volume 15, Number 6 (2002), 671-696.

### Relaxation results for higher order integrals below the natural growth exponent

Luca Esposito and Giuseppe Mingione

#### Abstract

We consider higher-order variational integrals of the type $$ \mathcal{F}(u,\Omega )=\int_{\Omega }f(x,u,D^{[k]}u,D^{k+1}u)\ dx$$ and study relaxation and lower semicontinuity properties of such functionals. In particular, under a bound of the type $$ 0\leq f(x,u,z_{1},z_{2},\ldots,z_{k+1}) \leq L(1+| z_{k+1}|^{q}) $$ the following relaxed energies are studied: \begin{eqnarray*} \mathcal{F}^{q,p}(u,\Omega) & = & \inf_{\{u_n\}} \Big \{\liminf_n \int_{\Omega}f(x,u_n,D^{[k]}u_n ,D^{k+1}u_n)\ dx \ : \\ & & u_n\in W^{k+1 ,q}(\Omega ;\Bbb R^d),\ u_n \rightharpoonup u \mbox{ in }W^{k+1 ,p}(\Omega ;\Bbb R^d) \Big \} \\ \mathcal{F}^{q,p}_{{loc}}(u,\Omega) & = & \inf_{\{u_n\}} \Big \{\liminf_n \int_{\Omega}f(x,u_n,D^{[k]}u_n ,D^{k+1}u_n)\ dx \ : \\ & & u_n\in W^{k+1 ,q}_{{loc}}(\Omega ;\Bbb R^d),\ u_n \rightharpoonup u \mbox{ in }W^{k+1 ,p}(\Omega ;\Bbb R^d) \Big \} \end{eqnarray*} with $\frac{q}{p} < \frac{Nk}{Nk-1}.$

#### Article information

**Source**

Differential Integral Equations, Volume 15, Number 6 (2002), 671-696.

**Dates**

First available in Project Euclid: 21 December 2012

**Permanent link to this document**

https://projecteuclid.org/euclid.die/1356060811

**Mathematical Reviews number (MathSciNet)**

MR1893841

**Zentralblatt MATH identifier**

1030.49013

**Subjects**

Primary: 49J45: Methods involving semicontinuity and convergence; relaxation

Secondary: 35A15: Variational methods 35J35: Variational methods for higher-order elliptic equations

#### Citation

Esposito, Luca; Mingione, Giuseppe. Relaxation results for higher order integrals below the natural growth exponent. Differential Integral Equations 15 (2002), no. 6, 671--696. https://projecteuclid.org/euclid.die/1356060811