A similarity invariant of a class of n-normal operators in terms of   K-theory
  In this paper, we prove an analogue of the Jordan canonical form theorem for a class of $n$-normal operators on complex separable Hilbert spaces in terms of von Neumann's reduction theory. This is a continuation of our study of bounded linear operators, the commutants of which contain bounded maximal abelian set of idempotents. Furthermore, we give a complete similarity invariant for this class of operators by $K$-theory for Banach algebras. 
Chunlan Jiang and Rui Shi
math.FA