Observations on the topological structure in 2d gravity coupled to minimal matter

By using a bosonization we uncover the topological gravity structure of Labastida, Pernici and Witten in ordinary 2d gravity coupled to (p, q) minimal models. We study the cohomology class associated with the fermionic charge of the topological gravity which is shown to be isomorphic to that of the total BRST charge. One of the ground ring generators of cM < 1 string theory is found to be in the equivariant cohomology of this fermionic charge.