  The central result of BCS theory are the Universal Ratios which do not depend
on physical parameters of the superconductor under study. Several attempts have
been made to introduce the van Hove Scenario within BCS theory but in none of
them the Universal Ratios of conventional superconductivity appear to be a
number independent of parameters. This fact prevents the precise definition of
a deviation from the BCS value for a particular superconductor. This concept is
at the basis of several applications of BCS theory in characterizing
conventional superconductors. We define a system that constitutes a weak
coupling limit that retains the essential features of the high-Tc oxides and
which does not differ in any essential way from other models widely used in
generalizations of BCS theory to high-Tc superconductors. The difference is
that we found a natural way of dealing with the mathematics of the problem so
as to get Universal Ratios in the same sense as in conventional
superconductivity.
