Cyclicity of Cowen-Douglas tuples
Jing Xu, Shanshan Ji, Yufang Xie, Kui Ji
TL;DR
The paper addresses the cyclicity of Cowen-Douglas tuples in $oldsymbol{eta}_n^m(oldsymbol{ abla})$ by integrating operator theory with complex geometry through the associated Hermitian holomorphic vector bundle $E_{oldsymbol{T}}$. The authors develop a constructive approach: for $oldsymbol{T}$ in $oldsymbol{eta}_1^m(oldsymbol{ abla})$ they build a cyclic vector from a holomorphic frame $oldsymbol{eta}(z)= extstyle abla a_oldsymbol{eta} z^oldsymbol{eta}$ and a rapidly decaying coefficient sequence, proving $oldsymbol{H}= ext{span}igl\{oldsymbol{T}^oldsymbol{eta}figrigr\}$. They then extend the result to general $n$ using spanning holomorphic cross-sections guaranteed by Eschmeier–Schmitt (2014), thereby showing that all commuting $m$-tuples in $oldsymbol{eta}_n^m(oldsymbol{ abla})$ are cyclic. This work deepens the link between holomorphic bundle theory and operator cyclicity, generalizing prior single-operator results to the Cowen–Douglas tuple setting with a complete cyclicity characterization.
Abstract
The study of Cowen-Douglas operators involves not only operator-theoretic tools but also complex geometry on holomorphic vector bundles. By leveraging the properties of holomorphic vector bundles, this paper investigates the cyclicity of Cowen-Douglas tuples and demonstrates conclusively that every such tuple is cyclic.
