Abstract
Some basic facts about the prepotential in the SW/Whitham theory are presented. Consideration begins from the abstract theory of quasiclassical
τ
-functions , which uses as input a family of complex spectral curves with a meromorphic differential
dS
, subject to the constraint
∂dS/∂(moduli)= holomorphic
, and gives as an output a homogeneous prepotential on extended moduli space. Then reversed construction is discussed, which is straightforwardly generalizable from spectral {\it curves} to certain complex manifolds of dimension
d>1
(like
K3
and
CY
families). Finally, examples of particular
N=2
SUSY gauge models are considered from the point of view of this formalism. At the end we discuss similarity between the
W
P
12
1,1,2,2,6
-\-Calabi-\-Yau model with
h
21
=2
and the
1d
SL(2)
Calogero/Ruijsenaars model, but stop short of the claim that they belong to the same Whitham universality class beyond the conifold limit.