most recent 30 from http://mathoverflow.net 2013-06-19T20:11:29Z http://mathoverflow.net/feeds/user/23737 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/96445/iterating-ultrapowers-of-c-algebras-the-calkin-algebra/97050#97050 ilijas farah 2012-05-15T20:56:16Z 2012-05-15T20:56:16Z

<p>The statement does not depend on separability of A. Actually in the Ge-Hadwin paper they explicitly state the result for C*-algebras of cardinality continuum. So under CH you have that the ultrapowers of C^1 are isomorphic to C^1. It is not completely trivial that C is not isomorphic to C^1. This was proved in arXiv:1112.3898 Countable saturation of corona algebras. Ilijas Farah, Bradd Hart. Also, if CH fails then every C*-algebra has 2^c nonisomorphic ultrapowers, so the sequence does not stabilize. This is in arXiv:0908.2790 Model theory of operator algebras I: Stability. Ilijas Farah, Bradd Hart, David Sherman.</p>