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The Connes spectrum of group actions and group gradings for certain quotient rings. (English) Zbl 0834.16038

Let \(H\) be a finite-dimensional, semisimple Hopf algebra over an algebraically closed field \(K\), and assume that \(H\) is either commutative or cocommutative. Let \(A\) be an \(H\)-module algebra which is semiprime right Goldie, and let \(Q(A)\) denote its classical right ring of quotients. The main result of this paper is that the Connes spectrum \(\text{CS}(A,H)\) is equal to \(\text{CS}(Q(A),H)\). In the same vein, if \(B\) is an \(H\)-semiprime, \(H\)-module algebra and if \(Q_H(B)\) denotes its \(H\)-symmetric ring of quotients, then it is shown here that \(\text{CS}(B,H)=\text{CS}(Q_H(B),H)\). These results are then applied to finite group actions and group gradings.

MSC:

16W30 Hopf algebras (associative rings and algebras) (MSC2000)
16W20 Automorphisms and endomorphisms
16S90 Torsion theories; radicals on module categories (associative algebraic aspects)
16W50 Graded rings and modules (associative rings and algebras)
16S40 Smash products of general Hopf actions
16S60 Associative rings of functions, subdirect products, sheaves of rings
Full Text: DOI

References:

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