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On two problems studied by A. Ambrosetti

David Arcoya, José Carmona (2006)

Journal of the European Mathematical Society

We study the Ambrosetti–Prodi and Ambrosetti–Rabinowitz problems.We prove for the first one the existence of a continuum of solutions with shape of a reflected C ( -shape). Next, we show that there is a relationship between these two problems.

On weakly A-harmonic tensors

Bianca Stroffolini (1995)

Studia Mathematica

We study very weak solutions of an A-harmonic equation to show that they are in fact the usual solutions.

One-dimensional symmetry for solutions of quasilinear equations in R 2

Alberto Farina (2003)

Bollettino dell'Unione Matematica Italiana

In this paper we consider two-dimensional quasilinear equations of the form div a u u + f u = 0 and study the properties of the solutions u with bounded and non-vanishing gradient. Under a weak assumption involving the growth of the argument of u (notice that arg u is a well-defined real function since u > 0 on R 2 ) we prove that u is one-dimensional, i.e., u = u ν x for some unit vector ν . As a consequence of our result we obtain that any solution u having one positive derivative is one-dimensional. This result provides a proof of...

One-dimensional symmetry of periodic minimizers for a mean field equation

Chang-Shou Lin, Marcello Lucia (2007)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

We consider on a two-dimensional flat torus T defined by a rectangular periodic cell the following equation Δ u + ρ e u T e u - 1 | T | = 0 , T u = 0 . It is well-known that the associated energy functional admits a minimizer for each ρ 8 π . The present paper shows that these minimizers depend actually only on one variable. As a consequence, setting λ 1 ( T ) to be the first eigenvalue of the Laplacian on the torus, the minimizers are identically zero whenever ρ min { 8 π , λ 1 ( T ) | T | } . Our results hold more generally for solutions that are Steiner symmetric, up to a translation....

Operator preconditioning with efficient applications for nonlinear elliptic problems

Janos Karátson (2012)

Open Mathematics

This paper is devoted to the numerical solution of nonlinear elliptic partial differential equations. Such problems describe various phenomena in science. An approach that exploits Hilbert space theory in the numerical study of elliptic PDEs is the idea of preconditioning operators. In this survey paper we briefly summarize the main lines of this theory with various applications.

Optimal regularity for the pseudo infinity Laplacian

Julio D. Rossi, Mariel Saez (2007)

ESAIM: Control, Optimisation and Calculus of Variations

In this paper we find the optimal regularity for viscosity solutions of the pseudo infinity Laplacian. We prove that the solutions are locally Lipschitz and show an example that proves that this result is optimal. We also show existence and uniqueness for the Dirichlet problem.

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