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Equivariant Maps and Bimodule Projections

Vern I. Paulsen
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Abstract

We construct a contractive, idempotent, MASA bimodule map on B(H), whose range is not a ternary subalgebra of B(H). Our method uses a crossed-product to reduce the existence of such an idempotent map to an analogous problem about the ranges of idempotent maps that are equivariant with respect to a group action and Hamana's theory of G-injective envelopes.

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Vern I. Paulsen. 2005-10-28. Equivariant Maps and Bimodule Projections. https://arxiv.org/abs/math/0510641

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