2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/103867We 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.15 pagesOperator Algebras46L05, 46A22text