On the existence of global solutions of second-order quasilinear elliptic inequalities

Abstract

We study the existence of global positive solutions of the differential inequalities $$ - \operatorname{div} A (x, u, \nabla u) \ge f (u) \quad \mbox{in } {\mathbb R}^n, $$ where $n \ge 2$ and $A$ is a Carath\'eodory function such that $$ (A (x, s, \zeta) - A (x, s, \xi))(\zeta - \xi) \ge 0, $$ $$ C_1 |\xi|^p \le \xi A (x, s, \xi), \quad |A (x, s, \xi)| \le C_2 |\xi|^{p-1}, \quad C_1, C_2 > 0, \; p > 1, $$ for almost all $x \in {\mathbb R}^n$ and for all $s \in {\mathbb R}$ and $\zeta, \xi \in {\mathbb R}^n$.