Uniqueness and parameter dependence of solutions of fourth-order four-point nonhomogeneous BVPs.
In this paper we discuss the uniqueness of positive solutions of the nonlinear second order system -u'' = g(v), -v'' = f(u) in (-R,R), u(±R) = v(±R) = 0 where f and g satisfy some appropriate conditions. Our result applies, in particular, to g(v) = v, f(u) = up, p > 1, or f(u) = λu + a1up1 + ... + akupk, with pj > 1, aj > 0 for j = 1, ..., k and 0 ≤ λ < μ12 where μ1 = π2/4R2.
We show the uniqueness of the very singular self-similar solution of the equationut - Δ pum + uq = 0.The result is carried out by studying the stationary associate equation and by introducing a suitable change of unknown. That allows to assume the zero-order perturbation term in the new equation to be monotone increasing. A careful study of the behaviour of solutions near the boundary of their support is also used in order to prove the main result.
The paper establishes sufficient conditions for the existence of solutions of Neumann’s problem for the differential equation which tend to the solution of the reduced problem on as
We consider multipoint and two-point BVPs for second order ordinary differential equations with a Carathéodory right hand side. We prove the existence of solutions provided there exist upper and lower solutions of the BVP and the upper solution is less than the lower one.