Remarks on the Continuity of the Local Minimizer of Scalar Integral Functionals With Nonstandard General Growth Conditions

Abstract

In this paper we show a regularity theorem for local minima of scalar integral functionals of the Calculus of Variations with nonstandard general growth conditions. Let us consider functionals in the following form\begin{equation*}\mathcal{F}\left[ u,\Omega \right] =\int\limits_{\Omega }f\left( x,u\left(x\right) ,\nabla u\left( x\right) \right),dx\end{equation*}where $f$: $\Omega \times\mathbb{R} \times\mathbb{R}^{N}\rightarrow\mathbb{R}$ is a Carath\'{e}odory function\ satisfying the inequalities\begin{equation*}\Phi \left( \left\vert z\right\vert \right) -c_{1}\leq f\left( x,s,z\right)\leq c_{2}\left[ 1+\left( \Phi ^{\ast }\left( \left\vert z\right\vert\right) \right) ^{\beta }+\left( \Phi ^{\ast }\left( \left\vert s\right\vert\right) \right) ^{\beta }\right]\end{equation*}for each $z\in\mathbb{R}^{N}$, $s\in\mathbb{R}$ and for $\mathcal{L}^{N}$-a. e. $x\in \Omega $, where $c_{1}$ and $c_{2}$ are two positive real constants, with $c_{1}<c_{2}$, $\Omega $ is an open subset of $\mathbb{R}^{N}$, $N\geq 2$, $\Phi \in \triangle _{2}^{m}\cap \nabla _{2}^{r}$ [Definition 6 and Definition 8], $1\leq r<m<N$ and the function $\Phi ^{\ast}$ is the Sobolev conjugate of $\Phi $ [Definition 12], $\beta $ is a positive real number that we will opportunely fix [Hypothesis $H_{1,f}$].