Such a highly non-linear problem would clearly benefitfrom the computational power of many layers. Unfortu-nately, back-propagation learning generally slows downby an order of magnitude every time a layer is added toa network.

There is a door in front of him. A yellow door. He knows the dream it used to lead to; he knows it well. But that’s not where it leads anymore. He does not know what is behind it anymore, and he is deathly afraid of finding out.