Annales Polonici Mathematici · 1993 · 66 citations · 5 references
Numerical AnalysisMethod Of Fundamental SolutionLower Solution MethodFree Boundary ProblemGeneralized UpperOscillation TheoryNonlinear EquationNonlinear Hyperbolic ProblemMonotone MethodPeriodic Travelling WaveCarathéodory FunctionsNonlinear ResonanceCarathéodory ConditionsNonlinear Functional Analysis
The purpose of this paper is to study the periodic boundary value problem -u''(t) = f(t,u(t),u'(t)), u(0) = u(2π), u'(0) = u'(2π) when f satisfies the Carathéodory conditions. We show that a generalized upper and lower solution method is still valid, and
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