abstract = "In this paper, the stock index S&P 500 is used to test
the predicting performance of genetic programming (GP)
and genetic programming neural networks (GPNN). While
both GP and GPNN are considered universal
approximators, in this practical financial application,
they perform differently. GPNN seemed to suffer the
overlearning (over fitting) problem more seriously than
GP; the latter outdid the former in all the
simulations.",