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Let A be a quasinilpotent operator on a Hilbert space and let every operator of the algebra generated by $A$ and $A^{*}$ have finite spectrum. Does then follow, that A is nilpotent ?

See also http://mathoverflow.net/questions/77177/quasinilpotence-and-finite-spectrum and http://mathoverflow.net/questions/35207/finite-dimensional-subalgebras-of-c-star-algebras

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Do you mean the (norm-)closed algebra generated by $A$ and $A*$? – Yemon Choi Oct 15 2011 at 1:50
@Yemon Choi : no, not the norm-closed algebra. I mean the non-commutative polynomials in A and $A^{*}$ . – jjcale Oct 15 2011 at 12:17

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