Rep⁡(H)\operatorname{Rep}(H) and the double

Rep⁡(H)\operatorname{Rep}(H) and the double

For a semisimple HH, rep_category(H) computes numerically, at any precision:

  • central primitive idempotents and matrix blocks, so the irreducible representations;
  • tensor products through Δ\Delta, so the fusion rules NabcN_{ab}^{c};
  • Clebsch–Gordan maps and the FF-symbols;
  • with an RR-matrix, the RR-symbols, and for a modular category SS and TT.

When the unit is not simple, Rep(H) is multifusion and is cut along 1=⨁i1i1 = \bigoplus_{i} 1_{i} into the fusion categories 1i⊗Rep⁡(H)⊗1i1_{i} \otimes \operatorname{Rep}(H) \otimes 1_{i}.

Drinfeld double

drinfeld_double_weak(H) builds D(H)=(H^op⊗H)/JD(H) = (\hat{H}^{\mathrm{op}} \otimes H)/J (Nikshych–Vainerman) with its canonical RR-matrix, exactly, and Rep⁡D(H)≃Z(Rep⁡H)\operatorname{Rep} D(H) \simeq \mathcal{Z}(\operatorname{Rep} H).

Hdim D(H)Checked
K[Z2]K[\mathbb{Z}_{2}], Sweedler H4H_{4}, K[Pair2]K[\mathrm{Pair}_{2}], KPair2K^{\mathrm{Pair}_{2}}, K[Pair3]K[\mathrm{Pair}_{3}]4, 16, 4, 4, 9every axiom, exactly
K[S3]K[S_{3}]36fusion rules and SS-matrix of the group double
Kac–Paljutkin H8H_{8}64rank 22: 8 invertibles, 14 of dimension 2
face algebra of Fibonacci47equal to the ladder algebra: blocks, fusion, SS
face algebra of Ising136equal to the ladder algebra: blocks, fusion, SS