Deep Belief Networks
   - Deep Belief Nets are currently the hot technique.
 
   - Apparently (it's a trade secret) this is what Google is using
       to learn just about everything (e.g. speech recognition, 
       robotic driving, and language translation). 
 
   - The idea is that you use a relatively sophisticated training
       algorithm on a network with many layers.
 
   - This enables you to use a lot of data productively to encode
       a really big problem.