Generalized Tambara-Yamagami categories
arXiv:1002.3166
Abstract
Fusion rules generalize groups by allowing multivalued multiplication. Groups are fusion rules of simple current index 1. We classify nilpotent (in the sense of Gelaki and Nikshych) fusion rules of simple current index 2, and characterize the associated fusion categories.
14 pages, no figures; references added, minor cosmetic changes on pp. 8 and 13