English

Orders of Nikshych's Hopf algebra

Quantum Algebra 2018-03-15 v3 Rings and Algebras Representation Theory

Abstract

Let pp be an odd prime number and KK a number field having a primitive pp-th root of unity ζ.\zeta. We prove that Nikshych's non-group theoretical Hopf algebra HpH_p, which is defined over Q(ζ)\mathbb{Q}(\zeta), admits a Hopf order over the ring of integers OK\mathcal{O}_K if and only if there is an ideal II of OK\mathcal{O}_K such that I2(p1)=(p)I^{2(p-1)} = (p). This condition does not hold in a cyclotomic field. Hence this gives an example of a semisimple Hopf algebra over a number field not admitting a Hopf order over any cyclotomic ring of integers. Moreover, we show that, when a Hopf order over OK\mathcal{O}_K exists, it is unique and we describe it explicitly.

Keywords

Cite

@article{arxiv.1405.2977,
  title  = {Orders of Nikshych's Hopf algebra},
  author = {Juan Cuadra and Ehud Meir},
  journal= {arXiv preprint arXiv:1405.2977},
  year   = {2018}
}

Comments

33 pages. Major changes in the presentation