In this paper we investigate the existence of positive solutions of the q-difference equation −D2 qu(t) = a(t) f(u(t)) with some boundary conditions by applying a fixed point theorem in cones. 1. Preliminaries In many of the mathematical models in science such as models of chemical problems, population or concentration in biology, and many problems in physics and economics, we need to investiga...

The paper deals with the existence of positive radial solutions for the p-Laplacian system div(|∇ui| ∇ui) + f (u1, . . . , un) = 0, |x| < 1, ui(x) = 0, on |x| = 1, i = 1, . . . , n, p > 1, x ∈ R . Here f , i = 1, . . . , n, are continuous and nonnegative functions. Let u = (u1, . . . , un), ‖u‖ = ∑n i=1|ui|, f i 0 = lim‖u‖→0 f(u) ‖u‖p−1 , f i ∞ = lim‖u‖→∞ f(u) ‖u‖p−1 , i = 1, . . . , n, f = (f1...

We consider the quasilinear problem −εpdiv(|∇u|p−2∇u) + V (z)up−1 = f(u) + up−1, u ∈W (R ), where ε > 0 is a small parameter, 1 < p < N , p∗ = Np/(N − p), V is a positive potential and f is a superlinear function. Under a local condition for V we relate the number of positive solutions with the topology of the set where V attains its minimum. In the proof we apply Ljusternik-Schnirelmann theory...

We give a negative answer to a conjecture of Korman on nonlinear elastic beam models. Moreover, by modifying the main conditions in the conjecture (generalizing the original ones at some points), we get positive results, that is, we obtain the existence of positive solutions for the models. 2000 Mathematics Subject Classification. 34B15.

Neutral delay differential equations contain the derivative of the unknown function both with and without delays. Some new phenomena can appear, hence the theory of neutral delay differential equations is even more complicated than the theory of non-neutral delay equations. The oscillatory behavior of the solutions of neutral systems is of importance in both the theory and applications, such as...

We study asymptotic behavior of solutions of general advanced differential systems y(t) = F(t, y(t)), where F : Ω → [Symbol: see text] (n) is a continuous quasi-bounded functional which satisfies a local Lipschitz condition with respect to the second argument and Ω is a subset in [Symbol: see text] × C(r)(n), C(r)(n) := C([0, r], [Symbol: see text] (n)), y t [Symbol: see text]C(r)(n), and y t (...

In paper, we study the existence of solutions for the singular pLaplacian equation` |u′′|p−2u′′ ́′′ − f(t, u) = 0, t ∈ (0, 1) u(0) = u(1) = 0, u′′(0) = u′′(1) = 0, where f(t, u) is singular at t = 0, 1 and at u = 0. We prove the existence of at least one solution.

This paper is concerned with the study of the existence of positive solutions for a Navier boundaryvalue problem involving the p-biharmonic operator; the right hand side of problem is a nonsmoothfunctional with variable parameters. The existence of at least three positive solutions is establishedby using nonsmooth version of a three critical points theorem for discontinuous functions. Our resul...