Journal of Operator Theory

Volume 56, Issue 2, Fall 2006 pp. 291-315.

Decompositions of reflexive bimodules over maximal abelian selfadjoint algebras

Authors: G.K. Eleftherakis
Author institution: Department of Mathematics, University of Athens, Panepistimiopolis, 15784, Greece

Summary: We generalize the notion of ``diagonal'' from the class of CSL algebras to masa bimodules. We prove that a reflexive masa bimodule decomposes as a sum of two bimodules, the diagonal and a module generalizing the $w^*$-closure of the Jacobson radical of a CSL algebra. The latter module turns out to be reflexive, a result which is new even for CSL algebras. We show that the projection onto the direct summand contained in the diagonal is contractive and preserves compactness and reduces rank of operators. Stronger results are obtained when the module is the reflexive hull of its rank-one subspace.

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