W Algebras from AdS/CFT Correspondence
  We consider a system of D5/D1 branes in the supergravity background AdS_3xS^3xX, where X is T^4 or K3. By investigating the structure of the missing states in the conformal description, we are able to extend the AdS/CFT correspondence to W algebras. As a test of this new formulation the results are compared to Hilbert schemes and more general supergravity backgrounds as deformations by D3-branes or six-dimensional Calabi-Yau manifolds. 
S. Korden