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Noetherian Centralizing Hopf Algebra Extensions and Finite Morphisms of Quantum Groups

E. S. Letzter
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Abstract

Let $A \subset H$ be a finite centralizing extension of noetherian Hopf algebras, and let $X$ denote the group of characters of $H$ that restrict to the augmentation map on $A$. Our main results provide necessary and sufficient conditions for the fibers of the canonical surjection from $spec H$ onto $spec A$ to coincide with the $X$-orbits in $spec H$. In particular, all of the fibers are $X$-orbits if and only if the fiber over the augmentation ideal of $A$ is an $X$-orbit. An application to the representation theory of quantum function algebras, at roots of unity, is presented.

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E. S. Letzter. 1999-05-10. Noetherian Centralizing Hopf Algebra Extensions and Finite Morphisms of Quantum Groups. https://arxiv.org/abs/math/9905056

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