sympy/sympy — pull request #2196 by Manoj-Kumar-S (2013-06-20 13:56:25+00:00)
Title: Heuristic 3

This tries to implement a heuristic given by @flacjacket to me, which assumer xi and eta to be bivariate polynomials in x and y. There seems to be some problem since, a few of the infinitesimals of the ODE, seem to fail the checkinfsol function.