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An extension of Putnam-Fuglede theorem for hyponormal operators. (English) Zbl 0591.47020

Let \(S\in B(H)\) and \(T^*\in B(K)\) be hyponormal and assume \(C^ n(S,T)A=0\) for some \(A\in B(K,H)\), where \(C^ n(S,T)\) denotes n times application of the commutator C(S,T):\( B(K,H)\to B(K,H)\) defined by \(C(S,T)A=SA-AT\). Then \(C(S,T)A=C(S^*,T^*)A=0\). The result can be extended to a larger class of operators.

MSC:

47B20 Subnormal operators, hyponormal operators, etc.
47B47 Commutators, derivations, elementary operators, etc.

References:

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