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Some relationships between an operator and its transform \(S_{r}(T)\)

  • Safa Menkad,
  • Sohir Zid

摘要

Let \( T \in \mathcal {B}(\mathcal {H})\) T B ( H ) be a bounded linear operator on a Hilbert space \( \mathcal {H}\) H , and let \( T = U \vert T \vert \) T = U | T | be the polar decomposition of T. For any \(r > 0\) r > 0 , the transform \(S_{r}(T)\) S r ( T ) is defined by \(S_{r}(T) = U \vert T \vert ^{r} U\) S r ( T ) = U | T | r U . In this paper, we discuss the transform \(S_{r}(T)\) S r ( T ) of some classes of operators such as p-hyponormal and rank one operators. We provide a new characterization of invertible normal operators via this transform. Afterwards, we investigate when an operator T and its transform \( S_{r}(T) \) S r ( T ) both have closed ranges, and show that this transform preserves the class of EP operators. Finally, we present some relationships between an EP operator T, its transform \( S_{r}(T)\) S r ( T ) and the Moore–Penrose inverse \( T^{+} \) T + .