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Given a pair of finite groups $F, G$ and a normalized 3-cocycle $omega$ of $G$, where $F$ acts on $G$ as automorphisms, we consider quasi-Hopf algebras defined as a cleft extension $Bbbk^G_omega#_c,Bbbk F$ where $c$ denotes some suitable cohomological data. When $Frightarrow overline{F}:=F/A$ is a quotient of $F$ by a central subgroup $A$ acting trivially on $G$, we give necessary and sufficient conditions for the existence of a surjection of quasi-Hopf algebras and cleft extensions of the type $Bbbk^G_omega#_c, Bbbk Frightarrow Bbbk^G_omega#_{overline{c}} , Bbbk overline{F}$. Our construction is particularly natural when $F=G$ acts on $G$ by conjugation, and $Bbbk^G_omega#_c Bbbk G$ is a twisted quantum double $D^{omega}(G)$. In this case, we give necessary and sufficient conditions that Rep($Bbbk^G_omega#_{overline{c}} , Bbbk overline{G}$) is a modular tensor category.
The notion of crossed product by a coquasi-bialgebra H is introduced and studied. The resulting crossed product is an algebra in the monoidal category of right H-comodules. We give an interpretation of the crossed product as an action of a monoidal c
We classify Lagrangian subcategories of the representation category of a twisted quantum double of a finite group. In view of results of 0704.0195v2 this gives a complete description of all braided tensor equivalent pairs of twisted quantum doubles o
We describe all fusion subcategories of the representation category of a twisted quantum double of a finite group. In view of the fact that every group-theoretical braided fusion category can be embedded into a representation category of a twisted qu
For a Hopf algebra B with bijective antipode, we show that the Heisenberg double H(B^*) is a braided commutative Yetter--Drinfeld module algebra over the Drinfeld double D(B). The braiding structure allows generalizing H(B^*) = B^{*cop}braid B to Hei
We discussed twisted quantum deformations of D=4 Lorentz and Poincare algebras. In the case of Poincare algebra it is shown that almost all classical r-matrices of S.Zakrzewski classification can be presented as a sum of subordinated r-matrices of Ab