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On the hessian of the optimal transport potential

Stefán Ingi Valdimarsson (2007)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

We study the optimal solution of the Monge-Kantorovich mass transport problem between measures whose density functions are convolution with a gaussian measure and a log-concave perturbation of a different gaussian measure. Under certain conditions we prove bounds for the Hessian of the optimal transport potential. This extends and generalises a result of Caffarelli. We also show how this result fits into the scheme of Barthe to prove Brascamp-Lieb inequalities and thus prove a new generalised Reverse...

On the isoperimetry of graphs with many ends

Christophe Pittet (1998)

Colloquium Mathematicae

Let X be a connected graph with uniformly bounded degree. We show that if there is a radius r such that, by removing from X any ball of radius r, we get at least three unbounded connected components, then X satisfies a strong isoperimetric inequality. In particular, the non-reduced l 2 -cohomology of X coincides with the reduced l 2 -cohomology of X and is of uncountable dimension. (Those facts are well known when X is the Cayley graph of a finitely generated group with infinitely many ends.)

On the isotropic constant of marginals

Grigoris Paouris (2012)

Studia Mathematica

We show that if μ₁, ..., μₘ are log-concave subgaussian or supergaussian probability measures in n i , i ≤ m, then for every F in the Grassmannian G N , n , where N = n₁ + ⋯ + nₘ and n< N, the isotropic constant of the marginal of the product of these measures, π F ( μ μ ) , is bounded. This extends known results on bounds of the isotropic constant to a larger class of measures.

On the ψ₂-behaviour of linear functionals on isotropic convex bodies

G. Paouris (2005)

Studia Mathematica

The slicing problem can be reduced to the study of isotropic convex bodies K with d i a m ( K ) c n L K , where L K is the isotropic constant. We study the ψ₂-behaviour of linear functionals on this class of bodies. It is proved that | | · , θ | | ψ C L K for all θ in a subset U of S n - 1 with measure σ(U) ≥ 1 - exp(-c√n). However, there exist isotropic convex bodies K with uniformly bounded geometric distance from the Euclidean ball, such that m a x θ S n - 1 | | · , θ | | ψ c n L K . In a different direction, we show that good average ψ₂-behaviour of linear functionals on an isotropic...

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