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Non-trivially isomorphic corona algebras

Speaker(s)
Saeed Ghasemi
Affiliation
IMPAN
Date
June 8, 2016, 4:15 p.m.
Room
room 5050
Seminar
Topology and Set Theory Seminar

It is well-known that there are Cech-Stone remainders (corona spaces) of locally compact spaces for which the question of whether they are homeomorphic is independent from ZFC (e.g., the Cech-Stone remainders of the ordinals \omega and \omega^2, with the order topology). Therefore by the Gelfand duality between compact Hausdorff spaces and commutative C*-algebras, there are commutative C*-algebras, for which the question of whether they are isomorphic is independent from ZFC.
I will present a tool in model theory for metric structures which allows us to find non-commutative C*-algebras -which are corona of product of full matrices- and are isomorphic under CH, but for non-trivial reasons. On the other hand it is consistent with ZFC that these corona algebras are only isomorphic if there is a trivial reason for it. 
The model theory tool used here is a generalization of the classical Feferman-Vaught Theorem to the reduced products of metric structures.