English

Approximate Carath{\'e}odory's theorem in uniformly smooth Banach spaces

Functional Analysis 2019-07-09 v2

Abstract

We study the 'no-dimension' analogue of Carath{\'e}odory's theorem in Banach spaces. We prove such a result together with its colorful version for uniformly smooth Banach spaces. It follows that uniform smoothness leads to a greedy de-randomization of Maurey's classical lemma \cite{pisier1980remarques}, which is itself a 'no-dimension' analogue of Carath{\'e}odory's theorem with a probabilistic proof. We find the asymptotically tight upper bound on the deviation of the convex hull from the kk-convex hull of a bounded set in LpL_p with 1<p21 < p \leq 2 and get asymptotically the same bound as in Maurey's lemma for LpL_p with 1<p<.1 < p < \infty.

Keywords

Cite

@article{arxiv.1904.06729,
  title  = {Approximate Carath{\'e}odory's theorem in uniformly smooth Banach spaces},
  author = {G. M. Ivanov},
  journal= {arXiv preprint arXiv:1904.06729},
  year   = {2019}
}