Semi-infinite cohomology in conformal field theory and 2d gravity
  We discuss various techniques for computing the semi-infinite cohomology of highest weight modules which arise in the BRST quantization of two dimensional field theories. In particular, we concentrate on two such theories -- the $G/H$ coset models and $2d$ gravity coupled to $c\leq 1$ conformal matter. (to appear in the proceedings of the XXV Karpacz Winter School) 
Peter Bouwknegt, Jim McCarthy, and Krzysztof Pilch