TY - JOUR ID - Tsouli2014 LB - Tsouli2014 AU - Tsouli, Najib AU - Darhouche, Omar TI - Existence and multiplicity results for nonlinear problems involving the p(x)-Laplace operator ST - Existence and multiplicity results for nonlinear problems involving the p(x)-Laplace operator JO - Opuscula Math. JA - Opuscula Math. JF - Opuscula Mathematica PY - 2014 VL - 34 IS - 3 SP - 621 EP - 638 DO - http://dx.doi.org/10.7494/OpMath.2014.34.3.621 UR - http://dx.doi.org/10.7494/OpMath.2014.34.3.621 AB - In this paper we study the following nonlinear boundary-value problem \[-\Delta_{p(x)} u=\lambda f(x,u) \quad \text{ in } \Omega,\] \[|\nabla u|^{p(x)-2}\frac{\partial u}{\partial \nu}+\beta(x)|u|^{p(x)-2}u=\mu g(x,u) \quad \text{ on } \partial\Omega,\] where \(\Omega\subset\mathbb{R}^N\) is a bounded domain with smooth boundary \(\partial\Omega\), \(\frac{\partial u}{\partial\nu}\) is the outer unit normal derivative on \(\partial\Omega\), \(\lambda, \mu\) are two real numbers such that \(\lambda^{2}+\mu^{2}\neq0\), \(p\) is a continuous function on \(\overline{\Omega}\) with \(\inf_{x\in \overline{\Omega}} p(x)\gt 1\), \(\beta\in L^{\infty}(\partial\Omega)\) with \(\beta^{-}:=\inf_{x\in \partial\Omega}\beta(x)\gt 0\) and \(f : \Omega\times\mathbb{R}\rightarrow \mathbb{R}\), \(g : \partial\Omega\times\mathbb{R}\rightarrow \mathbb{R}\) are continuous functions. Under appropriate assumptions on \(f\) and \(g\), we obtain the existence and multiplicity of solutions using the variational method. The positive solution of the problem is also considered. KW - critical points KW - variational method KW - \(p(x)\)-Laplacian KW - generalized Lebesgue-Sobolev spaces SN - 1232-9274 ER -