Learn a Line
   - You could pick two XO pairs, make a line between the pairs,
       and take the midpoint.
 
   - As those two points define a line, you've got a start.
 
   - This doesn't always work.
 
   - You could use a perceptron, with two inputs (X and Y), and
       adjust the weights for input.
 
   - A perceptron is just a IF neuron.  If it fires it's in Class 1, and
       if not in class 2.
 
   - Will this work on 3D data?  27D?