Varying bifurcation diagrams of positive solutions for a class of indefinite superlinear boundary value problems

In this work we analyze the existence, multiplicity and stability of positive solutions for a class of indefinite superlinear elliptic boundary value problems. The main contribution of this paper consists in the change of mind inherent to the fact of adding the superlinear amplitude $\varepsilon$ as an unfolding parameter. This change of mind allows us to unify many previous results obtained separately in the literature, it helps us to realize the global structure of the set of positive steady states, and provides us with a great variety of new general results. Our techniques can be applied to much more general equations and systems.