The early reception in France of the work of Poincaré and Lyapunov in the qualitative theory of differential equations
We analyze the chronological and conceptual evolution of the early use by Poincaré of tools, and in particular of in his qualitative theory of nonlinear differential equations. We show in this way that prior to his famous series of subsequent papers on Poincaré had already obtained or anticipated many important topological results.
We prove an Ambrosetti–Prodi type result for the periodic solutions of the equation , when is arbitrary and or when . The proof uses upper and lower solutions and the Leray–Schauder degree.
An analysis of the mathematical contributions of Juliusz Schauder through the writings of contemporary mathematicians, and in particular Leray, Hadamard, Banach, Randolph, Federer, Lorentz, Ladyzhenskaya, Ural’tseva, Orlicz, Gårding and Pietsch.
The paper surveys recent results obtained for the existence and multiplicity of radial solutions of Dirichlet problems of the type where is the open ball of center and radius in , and is continuous. Comparison is made with similar results for the Laplacian. Topological and variational methods are used and the case of positive solutions is emphasized. The paper ends with the case of a general domain.
Si dimostra che per una varietà quasi abeliana il corpo delle funzioni meromorfe ha grado di trascendenza infinito.
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