On the Solution of Topological Landau-Ginzburg Models with c=3c=3

The solution is given for the $c=3$ topological matter model whose underlying conformal theory has Landau-Ginzburg model W=-\qa (x^4 +y^4)+\af x^2y^2. While consistency conditions are used to solve it, this model is probably at the limit of such techniques. By using the flatness of the metric of the space of coupling constants I rederive the differential equation that relates the parameter \af\ to the flat coordinate $t$. This simpler method is also applied to the $x^3+y^6$-model.Comment: 7p