Induced conditional expectations of finite index on crossed product -algebras are considered which are non-algebraically of finite index. The characteristics of actions of (amenable) topological groups on compact Hausdorff spaces are investigated, ensuring the appearance of a well-defined induced conditional expectation on the corresponding commutative -a1gebra and its property to be of finite index. For this purpose Hilbert -module and topological techniques are used. Special emphasis is placed on discrete group actions.
Cite this article
Michael Frank, V.M. Manuilov, E.V. Troitsky, On Conditional Expectations Arising from Group Actions. Z. Anal. Anwend. 16 (1997), no. 4, pp. 831–850DOI 10.4171/ZAA/794