Abstract An upper and lower solution theory is presented for the Dirichlet boundary value problem \(y^{\prime\prime}+f(t,y,y^{\prime})=0\), \(0<t <1\) with \(y(0)=y(1)=0\).…
AbstractExistence and localization results are derived from Krasnoselskii’s compressionexpansion fixed point theorem in cones, for operator equations in spaces of…