Dear Sirs,
Please let me congratulate you on your amazing achievement in developing AlphaZero chess! As someone who completed a thesis in neural networks back in the 90's, I could not be more amazed at how far you have been able to advance the field.
I can't speak for the entire Stockfish team so I simply speak as one of its open source contributors. If you read other posts on this forum or talkchess.com however you may find that what I'm about to point out may mirror the sentiment of others in the computer chess community as well.
AlphaZero won the 100 game match against Stockfish very impressively by a total score of 28 wins and 72 draws and 0 loses. This translates to an Elo difference of 100. However the details of the match described in your paper show that this match might have been much closer and more interesting had it not been for some IMO rather unfair conditions. These might not be immediately obvious even to those using chess engines on a regular basis.
1) In the match version 8 of Stockfish was used which is now over a year old. The latest version of Stockfish is over 40 Elo stronger in fast self play.
http://tests.stockfishchess.org/tests/v ... 0ccbb8b6d8When consulted the Stockfish team always enters the latest version into serious competition such as TCEC.
2) The 1GB amount of memory used for the hash table on a 64 core machine with 1 minute per move is sorely inadequate. Stockfish displays the % of hash used so anyone can see how quickly it fills up. An reasonable amount of memory would likely have been around 16 times more at 16GB. The reason this is especially critical with many threads is because Stockfish uses the hash as the main mechanism through which all threads communicate(aka Lazy SMP). It is almost certain that this resulted in another significant Elo reduction in Stockfish.
3) Much effort has been put into making Stockfish understand which positions are critical and which are not. Based on this Stockfish manages its clock very carefully spending significantly more time on some positions during a game and very little on others. Disabling this feature and forcing Stockfish to use its time based on your same 1 minute for every move time control results in yet another large Elo reduction.
Since the Stockfish team wasn't contacted prior to the match I believe the issues outlined above were simply a result of unfamiliarity with the Stockfish engine. With the above issues corrected the 100 Elo gap should change quite significantly. I believe you are interested in a fair match more than winning and it is therefore my hope that a second proper rematch can be played for the benefit of both scientific research as well as the chess community. I wish to thank you for the tremendous contribution you have made to computer chess with a completely novel approach and hope that Stockfish has been a useful competitor for your testing. Please don't hesitate to contact myself or the Stockfish team in the future. We are your fans.
Sincerely
Michael Stembera(Fisherman)