A characterization of normal extensions for subfactors

Author:
Tamotsu Teruya

Journal:
Proc. Amer. Math. Soc. **120** (1994), 781-783

MSC:
Primary 46L37

DOI:
https://doi.org/10.1090/S0002-9939-1994-1207542-7

MathSciNet review:
1207542

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Abstract | References | Similar Articles | Additional Information

Abstract: Let be a tower of factors. If is a crossed product of by an outer action of a finite group on then it is well known that there exists a subgroup of such that . We prove in this paper that is a normal subgroup of if and only if there exist a finite group and an outer action of on such that .

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Additional Information

DOI:
https://doi.org/10.1090/S0002-9939-1994-1207542-7

Keywords:
Factor,
outer action,
crossed product,
Galois theory,
fixed point algebra,
conditional expectation

Article copyright:
© Copyright 1994
American Mathematical Society