In this note we prove the existence of extremal solutions of the quasilinear Neumann problem $-( \vert x^{^{\prime }}(t) \vert ^{p-2}x^{^{\prime }}(t))^{^{\prime }} = f(t,x(t),x ^{^{\prime }}(t))$, a.e. on $T$, $x^{^{\prime }}(0) = x^{^{\prime }}(b) =0$, $2\le p < \infty $ in the order interval $[\psi ,\varphi ]$, where $\psi $ and $\varphi $ are respectively a lower and an upper solution of the Neumann problem.
@article{107916, author = {Tiziana Cardinali and Nikolaos S. Papageorgiou and Raffaella Servadei}, title = {The Neumann problem for quasilinear differential equations}, journal = {Archivum Mathematicum}, volume = {040}, year = {2004}, pages = {321-333}, zbl = {1122.35030}, mrnumber = {2129954}, language = {en}, url = {http://dml.mathdoc.fr/item/107916} }
Cardinali, Tiziana; Papageorgiou, Nikolaos S.; Servadei, Raffaella. The Neumann problem for quasilinear differential equations. Archivum Mathematicum, Tome 040 (2004) pp. 321-333. http://gdmltest.u-ga.fr/item/107916/
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