English

Some more twisted Hilbert spaces

Functional Analysis 2020-12-14 v1

Abstract

We provide three new examples of twisted Hilbert spaces by considering properties that are "close" to Hilbert. We denote them Z(J)Z(\mathcal J), Z(S2)Z(\mathcal S^2) and Z(Ts2)Z(\mathcal T_s^2). The first space is asymptotically Hilbertian but not weak Hilbert. On the opposite side, Z(S2)Z(\mathcal S^2) and Z(Ts2)Z(\mathcal T_s^2) are not asymptotically Hilbertian. Moreover, the space Z(Ts2)Z(\mathcal T_s^2) is a HAPpy space and the technique to prove it gives a "twisted" version of a theorem of Johnson and Szankowski (Ann. of Math. 176:1987--2001, 2012). This is, we can construct a nontrivial twisted Hilbert space such that the isomorphism constant from its nn-dimensional subspaces to 2n\ell_2^n grows to infinity as slowly as we wish when nn\to \infty.

Keywords

Cite

@article{arxiv.2012.06411,
  title  = {Some more twisted Hilbert spaces},
  author = {Daniel Morales and Jesús Suárez},
  journal= {arXiv preprint arXiv:2012.06411},
  year   = {2020}
}
R2 v1 2026-06-23T20:54:17.351Z