A Smiley-type theorem for spectral operators of finite type

Abstract

In this short article, we mainly prove that, for any spectral operator $A$ of type $m$ on a complex Hilbert space, if a bounded operator $B$ lies in the collection of bounded linear operators that are in the $k$-centralizer of every bounded linear operator in the $l$-centralizer of $A$, where $k⩽l$ is two arbitrary positive integers satisfying $l⩾k$ as well as $l⩾2m+1$, then $B$ must belong to the von Neumann algebra generated by $A$ and identity operator. This result generalizes a matrix commutator theorem proved by M.\ F.\ Smiley. For this aim, Smiley-type operators are defined and studied.

10 pages