Transform Data by Example [video]
You know what this reminds me of?  Those trained neural-net things which, however many training examples you give it, always seem to find some way to “cheat” and not do what you want while still obeying all your training data correctly.Something like this:  Suppose we have a table of strings of digits, some including spaces, and we’d like to remove the spaces.  From  123 456
  234567
  345 678

to  123456
  234567
  345678

Now, what happens if it encounters, say  4567890

Would the result be unchanged (as we would probably want), or would it “cheat” and remove the middle “7” character, giving “456890”?