1. The existence of solutions for nonlinear elliptic equations: Simple proofs and extensions of a paper by Y. Shi.
- Author
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Xu, Xiaodan, de la Llave, Rafael, and Wang, Fenfen
- Subjects
- *
ELLIPTIC equations , *NONLINEAR equations - Abstract
The paper [39] uses the Craig-Wayne-Bourgain method to construct solutions of an elliptic problem involving parameters. The results of [39] include regularity assumptions on the perturbation and involve excluding parameters. The paper [39] also constructs response solutions to a quasi-periodically perturbed (ill-posed evolution) problem. In this paper, we use several classical methods (freezing of coefficients, alternative methods for nonlinear elliptic equations) to extend the results of [39]. We weaken the regularity assumptions on the perturbation and we describe the phenomena that happens for all parameters. In the ill-posed problem, we use a recently developed time-dependent center manifold theorem which allows to reduce the problem to a finite-dimensional ODE with quasi-periodic dependence on time. The bounded and sufficiently small solutions of these ODE give solutions of the ill-posed PDE. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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