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Accretive approximation in $$C^*$$-algebras. (English) Zbl 0838.47009
Summary: The problem of approximation by accretive elements in a unital $$C^*$$-algebra suggested by P. R. Halmos is substantially solved. The key idea is the observation that accretive approximation can be regarded as a combination of positive and selfadjoint approximation. The approximation results are proved both in the $$C^*$$-norm and in another, topologically equivalent norm.
##### MSC:
 47A58 Linear operator approximation theory 47B44 Linear accretive operators, dissipative operators, etc.
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