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Analyticity and flows in von Neumann algebras
Journal article   Open access   Peer reviewed

Analyticity and flows in von Neumann algebras

Richard I Loebl and Paul S Muhly
Journal of functional analysis, Vol.29(2), pp.214-252
1978
DOI: 10.1016/0022-1236(78)90007-1
url
https://doi.org/10.1016/0022-1236(78)90007-1View
Published (Version of record) Open Access

Abstract

Let B be a von Neumann algebra, let { α t } tεR be an ultraweakly continuous one-parameter group of ∗-automorphisms of B , and let U be the set of all A such that for each ϱ in B ∗, the function t → ϱ( α t ( A)) lies in H ∞( R . Then U is an ultraweakly closed subalgebra of B containing the identity which is proper and non-self-adjoint if { α t } tεR is not trivial. In this paper, a systematic investigation into the structure theory of U is begun. Two of the more note-worthy developments are these. First of all, conditions under which U is a subdiagonal algebra in B , in the sense of Arveson, are determined. The analysis provides a common perspective from which to view a large number of hitherto unrelated algebras. Second, the invariant subspace structure of U is determined and conditions under which U is a reductive subalgebra of B are found. These results are then used to produce examples where U is a proper, non-self-adjoint, reductive subalgebra of B . The examples do not answer the reductive algebra question, however, because although ultraweakly closed, the subalgebras are weakly dense in B .

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