This talk is based on an ongoing project in collaboration with Takasaki
and Tsuchiya. Our goal is to reconstruct and generalise results by
Eynard et al. from the standpoint of the integrable systems. Eynard,
Orantin and their collaborators found "topological recursion formulae"
to describe partition functions and correlation functions of the matrix
models, topological string theories etc., using simple algebro-geometric
data called "spectral curves". On the other hand, it is well known that
the partition functions of those theories are tau functions of
We have found that any solution of the KP hierarchy (with an asymptotic expansion parameter h) can be recovered by recursion relations from its "dispersionless" part (which corresponds to the genus zero part in topological theories) and a quantised contact transformation (which corresponds to the string equations) specifying the solution.