Taming Wild Extensions with Hopf Algebras
نویسندگان
چکیده
منابع مشابه
Hopf Algebra Extensions of Monogenic Hopf Algebras
William M. Singer has described a cohomology theory of connected Hopf algebras which classifies extensions of a cocommutative Hopf algebra by a commutative Hopf algebra in much the same way as the cohomology of groups classifies extensions of a group by an abelian group. We compute these cohomology groups for monogenic Hopf algebras, construct an action of the base ring on the cohomology groups...
متن کاملGalois extensions for coquasi-Hopf algebras
The notions of Galois and cleft extensions are generalized for coquasi-Hopf algebras. It is shown that such an extension over a coquasi-Hopf algebra is cleft if and only if it is Galois and has the normal basis property. A Schneider type theorem ([33]) is proven for coquasi-Hopf algebras with bijective antipode. As an application, we generalize Schauenburg’s bialgebroid construction for coquasi...
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We determine the structure of Hopf algebras that admit an extension of a group algebra by the cyclic group of order 2. We study the corepresentation theory of such Hopf algebras, which provide a generalization, at the Hopf algebra level, of the so called Tambara-Yamagami fusion categories. As a byproduct, we show that every semisimple Hopf algebra of dimension < 36 is necessarily group-theoreti...
متن کاملA Morita context and Galois extensions for Quasi-Hopf algebras
If H is a finite dimensional quasi-Hopf algebra and A is a left H-module algebra, we prove that there is a Morita context connecting the smash product A#H and the subalgebra of invariants A . We define also Galois extensions and prove the connection with this Morita context, as in the Hopf case.
متن کاملCrossed Products and Cleft Extensions for Coquasi-hopf Algebras
The notion of crossed product with a coquasi-Hopf algebra H is introduced and studied. The result of such a crossed product is an algebra in the monoidal category of right H-comodules. We give necessary and sufficient conditions for two crossed products to be equivalent. Then, two structure theorems for coquasi Hopf modules are given. First, these are relative Hopf modules over the crossed prod...
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ژورنال
عنوان ژورنال: Transactions of the American Mathematical Society
سال: 1987
ISSN: 0002-9947
DOI: 10.2307/2000707