English

Random Matrices and Subexponential Operator Spaces

Operator Algebras 2014-12-23 v3 Mathematical Physics math.MP Probability

Abstract

We introduce and study a generalization of the notion of exact operator space that we call subexponential. Using Random Matrices we show that the factorization results of Grothendieck type that are known in the exact case all extend to the subexponential case, but we exhibit (a continuum of distinct) examples of non-exact subexponential operator spaces, as well as a CC^*-algebra that is subexponential with constant 1 but not exact. We also show that OHOH, R+CR+C and max(2)\max(\ell_2) (or any other maximal operator space) are not subexponential.

Keywords

Cite

@article{arxiv.1212.2053,
  title  = {Random Matrices and Subexponential Operator Spaces},
  author = {Gilles Pisier},
  journal= {arXiv preprint arXiv:1212.2053},
  year   = {2014}
}

Comments

This paper is extracted from an older version of "Quantum expanders and geometry of operator spaces". v2: Some corrections. A notable addition is Theorem 7.13, due to Mikael de la Salle, showing that the C* algebra generated by the block direct sum of unitary random matrices is a.s. subexponential with constant 1, in analogy with what we proved in the Gaussian case. v3: minor corrections

R2 v1 2026-06-21T22:51:29.741Z