2 Tau-function on spaces of Abelian differentials over Riemann surfaces 7 2.1 Spaces of holomorphic differentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Variational formulas on Hg(k1, . . . , kM ) . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3 Basic Beltrami differentials for Hg(k1, . . . , kM ) . . . . . . . . . . . . . . . . . . . . . . 11 2.4 Definition of...