k-hyponormality of multivariable weighted shifts
arXiv:math/0507071
Abstract
We characterize joint k-hyponormality for 2-variable weighted shifts. Using this characterization we construct a family of examples which establishes and illustrates the gap between k-hyponormality and (k+1)-hyponormality for each k>=1. As a consequence, we obtain an abstract solution to the Lifting Problem for Commuting Subnormals.
13 pages; to appear in J. Funct. Anal