On the Flatness of Semi-Cubically Hyponormal Weighted Shifts
Chunji Li, Ji-Hye Ahn · Kyungpook mathematical journal · 2008
Let Wα be a weighted shift with positive weight sequence α = {αi} ∞ i=0 .The semi-cubical hyponormality of Wα is introduced and some flatness properties of Wα are discussed in this note.In particular, it is proved that if αn = αn+1 for some n ≥ 1, then α n+k = αn for all k ≥ 1.