Two-parameter quantum groups and quantum planes
  Usually the generators of a quantum group are assumed to be commutative with the noncommuting coordinates of a quantum plane. We have relaxed the assumption and investigated its consequences. Not only does a two-parameter quantum group arise naturally, but also the formulation leads us to many probable quantum planes associated with a quantum group. Several examples are presented. 
Sunggoo Cho, Sang-jun Kang, Chung-hum Kim, and Kwang Sung Park