You will see here how Stockfish improvements are tested. http://tests.stockfishchess.org/tests http://tests.stockfishchess.org/tests Some code or weight is ch

You will see here how Stockfish improvements are tested. http://tests.stockfishchess.org/tests http://tests.stockfishchess.org/tests Some code or weight is changed, then they have it play to see if it leads to better performance. An exhaustive, sort of manual work. On the other hand Deepmind's bot is fully automated and they have it just running day and night improving itself on a large hardware configuration.