Some more twisted Hilbert spaces

Abstract

We provide three new examples of twisted Hilbert spaces by considering properties that are "close" to Hilbert. We denote them \(Z(\mathcal J)\), \(Z(\mathcal S^2)\) and \(Z(\mathcal T_s^2)\). The first space is asymptotically Hilbertian but not weak Hilbert. On the opposite side, \(Z(\mathcal S^2)\) and \(Z(\mathcal T_s^2)\) are not asymptotically Hilbertian. Moreover, the space \(Z(\mathcal T_s^2)\) 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 \(n\)-dimensional subspaces to \(\ell_2^n\) grows to infinity as slowly as we wish when \(n\to \infty\).