Search results for "Dvoretzky's theorem"

The variance of the $\ell _p^n$-norm of the Gaussian vector, and Dvoretzky’s theorem

2019

Lineability of non-differentiable Pettis primitives

2014

Let \(X\) be an infinite-dimensional Banach space. In 1995, settling a long outstanding problem of Pettis, Dilworth and Girardi constructed an \(X\)-valued Pettis integrable function on \([0,1]\) whose primitive is nowhere weakly differentiable. Using their technique and some new ideas we show that \(\mathbf{ND}\), the set of strongly measurable Pettis integrable functions with nowhere weakly differentiable primitives, is lineable, i.e., there is an infinite dimensional vector space whose nonzero vectors belong to \(\mathbf{ND}\).

The variance of the ℓnp-norm of the Gaussian vector, and Dvoretzky's theorem

2018

Let n be a large integer, and let G be the standard Gaussian vector in Rn. Paouris, Valettas and Zinn (2015) showed that for all p∈[1,clogn], the variance of the ℓnp-norm of G is equivalent, up to a constant multiple, to 2ppn2/p−1, and for p∈[Clogn,∞], to (logn)−1. Here, C,c>0 are universal constants. That result left open the question of estimating the variance for p logarithmic in n. In this paper, the question is resolved by providing a complete characterization of Var∥G∥p for all p. It is shown that there exist two transition points (windows) in which the behavior of Var∥G∥p changes significantly. Some implications of the results are discussed in the context of random Dvoretzky's theore…