Hopf Algebras and Congruence Subgroups
Author | : Yorck Sommerhäuser |
Publisher | : American Mathematical Soc. |
Total Pages | : 146 |
Release | : 2012 |
Genre | : Mathematics |
ISBN | : 0821869132 |
Download Hopf Algebras and Congruence Subgroups Book in PDF, Epub and Kindle
We prove that the kernel of the action of the modular group on the center of a semisimple factorizable Hopf algebra is a congruence subgroup whenever this action is linear. If the action is only projective, we show that the projective kernel is a congruence subgroup. To do this, we introduce a class of generalized Frobenius-Schur indicators and endow it with an action of the modular group that is compatible with the original one.