Would it not be beneficial to the deepmind team to open at least the non-distributed version to the public to allow for training on more players? I was surprised to learn that the training set was strong amateur internet play, why not train on the database of the history of pro games?
That's just the initial training set, to get things started.
Alphago learns mostly from playing against itself. (And in the future they are planning to remove the crutch of starting with human generated data entirely.)
