A non-extendable bounded linear map between C*-algebras

Authors
Ozawa, N
Citation
N. Ozawa, A non-extendable bounded linear map between C*-algebras, P EDIN MATH, 44, 2001, pp. 241-248
Citations number
21
Categorie Soggetti
Mathematics
Journal title
PROCEEDINGS OF THE EDINBURGH MATHEMATICAL SOCIETY
ISSN journal
00130915 → ACNP
Volume
44
Year of publication
2001
Part
2
Pages
241 - 248
Database
ISI
SICI code
0013-0915(200106)44:<241:ANBLMB>2.0.ZU;2-N
Abstract
We present an example of a C*-subalgebra A of B(H) and a bounded linear map from A to B(K) which does not admit any bounded linear extension. This gen eralizes the result of Robertson and gives the answer to a problem raised b y Pisier. Using the same idea, we compute the exactness constants of some Q -spaces. This solves a problem raised by Oikhberg. We also construct a Q-sp ace which is not locally reflexive.