Two Generalizations of Stampacchia Lemma and Applications
Han Yingxiao, Fang Mi, Xia Liuye, Gao Hongya
Abstract
We present two generalizations of the classical Stampacchia Lemma which contain a non-decreasing non-negative function $g$, and give applications. As a first application, we deal with variational integrals of the form $$ {\cal J} (u;Ω) = \int_Ω\ f(x,Du{(x)})dx. $$ We consider a minimizer $u: Ω\subset \mathbb R^n \to \mathbb R $ among all functions with a fixed boundary value $u_{\ast }$ on $\partial Ω$. Under some nonstandard growth conditions of the integrand $f(x,ξ)$ we derive some regularity results; as a second application, we consider elliptic equations of the form $$ \begin{cases} -\mbox {div} \left( a(x, u(x)) D u(x) \right) = f(x), & x \in Ω, u(x) = 0, & x \in {\partial Ω}, \end{cases} $$ under the conditions $$ \frac {α}{(1+|s|) ^θ\ln ^θ(e+|s|)} \le a (x,s) \le β, \ \ \ 0<α\le β<\infty, \ θ\ge 0, $$ we obtain some regularity properties of its weak solutions.
