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On the Moser-Onofri and Prékopa-Leindler inequalities.

Alessandro Ghigi (2005)

Collectanea Mathematica

Using elementary convexity arguments involving the Legendre transformation and the Prékopa-Leindler inequality, we prove the sharp Moser-Onofri inequality, which says that1/16π ∫|∇φ|2 + 1/4π ∫ φ - log (1/4π ∫ eφ) ≥ 0for any funcion φ ∈ C∞(S2).

On the multiplicity of eigenvalues of conformally covariant operators

Yaiza Canzani (2014)

Annales de l’institut Fourier

Let ( M , g ) be a compact Riemannian manifold and P g an elliptic, formally self-adjoint, conformally covariant operator of order m acting on smooth sections of a bundle over M . We prove that if P g has no rigid eigenspaces (see Definition 2.2), the set of functions f C ( M , ) for which P e f g has only simple non-zero eigenvalues is a residual set in C ( M , ) . As a consequence we prove that if P g has no rigid eigenspaces for a dense set of metrics, then all non-zero eigenvalues are simple for a residual set of metrics in the C -topology....

On the natural transformations of Weil bundles

Ivan Kolář (2013)

Archivum Mathematicum

First we deduce some general results on the covariant form of the natural transformations of Weil functors. Then we discuss several geometric properties of these transformations, special attention being paid to vector bundles and principal bundles.

On the necessity of gaps

Hiroshi Matano, Paul Rabinowitz (2006)

Journal of the European Mathematical Society

Recent papers have studied the existence of phase transition solutions for Allen–Cahn type equations. These solutions are either single or multi-transition spatial heteroclinics or homoclinics between simpler equilibrium states. A sufficient condition for the construction of the multitransition solutions is that there are gaps in the ordered set of single transition solutions. In this paper we explore the necessity of these gap conditions.

On the nonlinear Neumann problem at resonance with critical Sobolev nonlinearity

J. Chabrowski, Shusen Yan (2002)

Colloquium Mathematicae

We consider the Neumann problem for the equation - Δ u - λ u = Q ( x ) | u | 2 * - 2 u , u ∈ H¹(Ω), where Q is a positive and continuous coefficient on Ω̅ and λ is a parameter between two consecutive eigenvalues λ k - 1 and λ k . Applying a min-max principle based on topological linking we prove the existence of a solution.

On the notion of potential for mappings between linear spaces. A generalized version of the Poincaré lemma

Tullio Valent (2003)

Bollettino dell'Unione Matematica Italiana

An approach to the theory of linear differential forms in a radial subset of an (arbitrary) real linear space X without a Banach structure is proposed. Only intrinsic (partially linear) topologies on X are (implicitly) involved in the definitions and statements. Then a mapping F : U X Y , with X , Y real linear spaces and U a radial subset of X , is considered. After showing a representation theorem of those bilinear forms , on X × Y for which x , y = 0 ...

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