A cocycle for the comultiplication on the quantum SU(2) group
  For the family Delta_q, q in [0,1), of the SU_q(2)-comultiplications on the C*-algebra A\cong C(SU_q(2)), we show that there exist unitary operators Omega_q such that Delta_q(x)=Omega_q Delta_0(x) (Omega_q)* for x in A. 
Wojciech Szymanski