We established the existence of weak solutions of the fourth-order elliptic equation of the form <Equation ID="Equa1"> <EquationSource Format="TEX">$$\begin{aligned} \Delta ^2 u -\Delta u + a(x)u=\lambda b(x) f(u) + \mu g (x, u), \qquad x \in \mathbb{R }^N, u \in H^2(\mathbb{R }^N), \end{aligned}$$</EquationSource> </Equation>where <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$$\lambda $$</EquationSource> </InlineEquation> is a positive parameter, <InlineEquation ID="IEq4">...</inlineequation></equationsource></inlineequation></equationsource></equation>

In this paper, we prove the existence of infinitely many solutions to differential problems where both the equation and the conditions are Sturm–Liouville type. The approach is based on critical point theory. Copyright Springer Science+Business Media, LLC. 2012

It is well known that the concept of "determinacy"-a single stable solution-plays a major role in contemporary monetary policy analysis. But while determinacy is desirable, other things equal, it is not necessary for a solution to be plausible and is not sufficient for a solution to be...