Hopf bimodules and Yetter-Drinfeld modules of Hopf algebroids
Xiao Han
TL;DR
This work extends the theory of Hopf bimodules and Yetter-Drinfeld modules from Hopf algebras to Hopf algebroids, establishing (pre-)braided and braided monoidal structures on their categories. It proves an equivalence between the categories of Hopf bimodules and Yetter-Drinfeld modules over a Hopf algebroid, and develops a duality theory for finitely generated projective Yetter-Drinfeld modules via dual pairings. The results provide foundational categorical tools for quantum groupoids and potential differential-geometric constructions (e.g., quantum Atiyah Lie algebroids) within the Hopf algebroid setting. Together, these contributions offer a robust framework for studying quantum symmetries and their modules in a generalized algebroid context, with implications for quantum geometry and cyclic (co)homology theories.
Abstract
We construct Hopf bimodules and Yetter-Drinfeld modules of Hopf algebroids as a generalization of the theory for Hopf algebras. More precisely, we show that the categories of Hopf bimodules and Yetter-Drinfeld modules over a Hopf algebroid are equivalent (pre-)braided monoidal categories. Moreover, we also study the duality between finitely generated projective Yetter-Drinfeld modules.
