Principal bundles and group extensions with applications to Hopf algebras
نویسندگان
چکیده
منابع مشابه
Groupoid extensions, principal 2-group bundles and characteristic classes
We give an explicit description of a 1-1 correspondence between Morita equivalence classes of, on the one hand, principal 2-group [G → Aut(G)]bundles over Lie groupoids (i.e. [G → Aut(G)]-bundles over differentiable stacks) and, on the other hand, centralG-extensions of Lie groupoids (i.e. Ggerbes over differentiable stacks). We also introduce universal characteristic classes for 2-group bundle...
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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...
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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...
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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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This expository article presents a unified ring theoretic approach, based on the theory of Frobenius algebras, to a variety of results on Hopf algebras. These include a theorem of S. Zhu on the degrees of irreducible representations, the so-called class equation, the determination of the semisimplicity locus of the Grothendieck ring, the spectrum of the adjoint class and a non-vanishing result ...
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ژورنال
عنوان ژورنال: Journal of Pure and Applied Algebra
سال: 1973
ISSN: 0022-4049
DOI: 10.1016/0022-4049(73)90011-x