Manin pairs and topological conformal field theory

We study a general class of topological conformal held theories which are consistent string backgrounds, and we present some examples which arise as coset models associated to what Drinfeld has called a Manin pair. These models are obtained by twisting a superconformal field theory in which the OPE G^-(z) · G^-(w) has a simple pole, whose residue is a BRST commutator. (The resulting chiral algebra has been studied by Kazama.) We show how this type of topological conformal field theory may be coupled to topological gravity, retrieving a full twisted N = 2 superconformal symmetry in the process.