15 citations · 42 across the 14 of their papers we have counts for
4 papers · 1 filter
On the Central Charge of a Factorizable Hopf Algebra
Yorck Sommerhaeuser, Yongchang Zhu
For a semisimple factorizable Hopf algebra over a field of characteristic zero, we show that the value that an integral takes on the inverse Drinfel'd element differs from the valu…
Hopf Algebras and Congruence Subgroups
Yorck Sommerhaeuser, Yongchang Zhu
We prove that the kernel of the natural action of the modular group on the center of the Drinfel'd double of a semisimple Hopf algebra is a congruence subgroup. To do this, we intr…
On Higher Frobenius-Schur Indicators
Yevgenia Kashina, Yorck Sommerhaeuser, Yongchang Zhu
We study the higher Frobenius-Schur indicators of modules over semisimple Hopf algebras, and relate them to other invariants as the exponent, the order, and the index. We prove var…
Self-dual modules of semisimple Hopf algebras
Yevgenia Kashina, Yorck Sommerhaeuser, Yongchang Zhu
We prove that, over an algebraically closed field of characteristic zero, a semisimple Hopf algebra that has a nontrivial self-dual simple module must have even dimension. This gen…