English

Volumes of unit balls of mixed sequence spaces

Functional Analysis 2015-06-26 v2

Abstract

The volume of the unit ball of the Lebesgue sequence space pm\ell_p^m is very well known since the times of Dirichlet. We calculate the volume of the unit ball in the mixed norm qn(pm)\ell^n_q(\ell_p^m), whose special cases are nowadays popular in machine learning under the name of group lasso. We consider the real as well as the complex case. The result is given by a closed formula involving the gamma function, only slightly more complicated than the one of Dirichlet. We close by an overview of open problems.

Keywords

Cite

@article{arxiv.1505.05867,
  title  = {Volumes of unit balls of mixed sequence spaces},
  author = {Henning Kempka and Jan Vybíral},
  journal= {arXiv preprint arXiv:1505.05867},
  year   = {2015}
}