Reduction of HKT-Structures
  KT-geometry is the geometry of a Hermitian connection whose torsion is a 3-form. HKT-geometry is the geometry of a hyper-Hermitian connection whose torsion is a 3-form. We identify non-trivial conditions for a reduction theory for these types of geometry. 
Gueo Grantcharov, George Papadopoulos, Yat Sun Poon