Sub-Super Solutions Method Combined with Schauder’s Fixed Point for Existence of Positive Weak Solutions for Anisotropic Non-Local Elliptic Systems (original) (raw)

Positive solutions for sublinear elliptic equations

Colloquium Mathematicum, 2002

The existence of a positive radial solution for a sublinear elliptic boundary value problem in an exterior domain is proved, by the use of a cone compression fixed point theorem. The existence of a nonradial, positive solution for the corresponding nonradial problem is obtained by the sub-and supersolution method, under an additional monotonicity assumption.

Existence of Strictly Positive Solutions for Sublinear Elliptic Problems in Bounded Domains

Advanced Nonlinear Studies, 2014

Let Ω be a smooth bounded domain in RN and let m be a possibly discontinuous and unbounded function that changes sign in Ω. Let f : [0,∞) → [0,∞) be a nondecreasing continuous function such that k1ξp ≤ f (ξ) ≤ k2ξp for all ξ ≥ 0 and some k1, k2 > 0 and p ∈ (0, 1). We study existence and nonexistence of strictly positive solutions for nonlinear elliptic problems of the form −Δu = m(x) f (u) in Ω, u = 0 on ∂Ω.

Nonexistence of positive solutions to nonlinear nonlocal elliptic systems

Journal of Mathematical Analysis and Applications, 2008

In this paper we consider the question of nonexistence of nontrivial solutions for nonlinear elliptic systems involving fractional diffusion operators. Using a weak formulation approach and relying on a suitable choice of test functions, we derive sufficient conditions in terms of space dimension and systems parameters. Also, we present three main results associated to three different classes of systems.

On the existence of positive solutions for a class of non–selfadjoint elliptic boundary value problems

Applicable Analysis, 1989

We consider a class of non-selfadjoint el1iptic boundary value problems on a bounded domain. Combining results on weighted eigenvalue problems for non-selfadjoint operators with a general form 0f the method of sub-supersolutions we prove existence of a positive solution provided that the nonlinearity f(x,u) satisfies a suitable "crossing condition" when u varies from zero to infinity

Positive solutions of some nonlinear elliptic problems in unbounded domain

2004

We study the existence of positive solutions of the nonlinear elliptic equation Δu + φ(.,u) = 0, in an unbounded domain D in R n , n > 3, with compact boundary. Our purpose is to give some existence results for the above equation with some boundary values, where the nonlinear term φ(t,x) satisfies some appropriate conditions related to a certain Kato class K ∞ (D). We give also some estimates on the solution u.