210 research outputs found

    An asymmetric Putnam-Fuglede theorem for *-paranormal operators

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    The well-known asymmetric form of Putnam-Fuglede theorem asserts that if AA and BB are bounded normal operators and AX=XB∗AX = XB^* for some bounded operator XX, then A∗X=XBA^*X = XB. In this paper we showed that the above theorem does not hold for paranormal operator AA, even if we assume that BB has to be unitary and an operator XX is taken from Hilbert-Schmidt class. Additionally, we showed the similar resualt for *-paranormal operators.Comment: 5 page

    On the converse of the Fuglede-Putnam theorem

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