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The concentration-compactness principle in the calculus of variations. The limit case, Part II.

Pierre-Louis Lions — 1985

Revista Matemática Iberoamericana

This paper is the second part of a work devoted to the study of variational problems (with constraints) in functional spaces defined on domains presenting some (local) form of invariance by a non-compact group of transformations like the dilations in R. This contains for example the class of problems associated with the determination of extremal functions in inequalities like Sobolev inequalities, convolution or trace inequalities... We show how the concentration-compactness principle and method...

The concentration-compactness principle in the calculus of variations. The limit case, Part I.

Pierre-Louis Lions — 1985

Revista Matemática Iberoamericana

After the study made in the locally compact case for variational problems with some translation invariance, we investigate here the variational problems (with constraints) for example in R where the invariance of R by the group of dilatations creates some possible loss of compactness. This is for example the case for all the problems associated with the determination of extremal functions in functional inequalities (like for example the Sobolev inequalities). We show here how the concentration-compactness...

Remarques sur les équations linéaires elliptiques du second ordre sous forme divergence dans les domaines non bornés

Pierre Louis Lions — 1985

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Si dimostra resistenza e l'unicità della soluzione del problema A u = f , u H 0 1 ( Ω ) nel caso in cui Ω è un aperto di n non limitato, A è un operatore variazionale ellittico del secondo ordine a coefficienti misurabili e limitati e f appartiene a H - 1 ( Ω ) .

Remarques sur les équations linéaires elliptiques du second ordre sous forme divergence dans les domaines non bornés

Pierre Louis Lions — 1985

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Si dimostra resistenza e l'unicità della soluzione del problema A u = f , u H 0 1 ( Ω ) nel caso in cui Ω è un aperto di n non limitato, A è un operatore variazionale ellittico del secondo ordine a coefficienti misurabili e limitati e f appartiene a H - 1 ( Ω ) .

Sur les mesures de Wigner.

Pierre-Louis LionsThierry Paul — 1993

Revista Matemática Iberoamericana

We study the properties of the Wigner transform for arbitrary functions in L or for hermitian kernels like the so-called density matrices. And we introduce some limits of these transforms for sequences of functions in L, limits that correspond to the semi-classical limit in Quantum Mechanics. The measures we obtain in this way, that we call Wigner measures, have various mathematical properties that we establish. In particular, we prove they satisfy, in linear situations (Schrödinger equations) or...

Diffusive limit for finite velocity Boltzmann kinetic models.

Pierre Louis LionsGiuseppe Toscani — 1997

Revista Matemática Iberoamericana

We investigate, in the diffusive scaling, the limit to the macroscopic description of finite-velocity Boltzmann kinetic models, where the rate coefficient in front of the collision operator is assumed to be dependent of the mass density. It is shown that in the limit the flux vanishes, while the evolution of the mass density is governed by a nonlinear parabolic equation of porous medium type. In the last part of the paper we show that our method adapts to prove the so-called Rosseland approximation...

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