Harnack type inequalities and multiple solutions in cones of nonlinear problems


The paper presents an abstract theory regarding operator equations and systems in ordered Banach spaces. We obtain existence, localization and multiplicity results of positive solutions using Krasnosel’skii’s fixed point theorem in cones, and a Harnack type inequality. Concerning systems, the localization is established by the vector version of Krasnosel’skii’s theorem, where the compression-expansion conditions are expressed on components. The approach is sufficiently general to cover and unify a large number of results on particular classes of problems. It also can guide future research in this direction.


Diana-Raluca Herlea
Babeș-Bolyai University, Cluj-Napoca, Romania

Donal O’Regan
National University of Ireland, Galway, Ireland

Radu Precup
Babes-Bolyai University, Cluj-Napoca, Romania


Boundary value problem; positive solution; Harnack inequality; Krasnosel’skii’s fixed point theorem in cones; operator equation

Paper coordinates

D.-R. Herlea, D. O’Regan, R. Precup, Harnack type inequalities and multiple solutions in cones of nonlinear problems, Z. Anal. Anwend. 39 (2020), 151-170, https://doi.org/10.4171/zaa/1655



About this paper


Zeitschrift fur Analysis und ihre Anwendunge



Publisher Name

European Mathematical Society

Print ISSN


Online ISSN


google scholar link

Related Posts