hyatt wrote:Null-move is about +80 in Crafty. Measured carefully on the cluster. LMR is right at +100 today. By itself with no null-move. Again measured carefully on our cluster. One year ago it was +80, but some recent changes boosted this a bit. But even more importantly, if you already have null-move, LMR is only about +50 more. It is nowhere near +200 or beyond...
You speak of Crafty while I had Rybka, Stockfish and Ippo.* in mind. Apparently they seem to profit a lot more.
How do you figure that? Don Beal wrote the first paper on null-move. Fruit was the first known instance of LMR (known as history pruning). So I am not exactly sure how you say they contributed the most.
There is no LMR in Fruit only "history reductions" based on counters. This idea originally came from Rudolf Huber (SOS) and was successfully implemented by SMK in Shredder. But the idea became known and it got the attention of everybody because of the Fruit sources.
I think that Shredder was the first program to use LMR. It's why Shredder ruled the world for a couple of years. Then (again) the idea of LMR became known (Stephen likes to talk apparently) and Tord eventually gave it the public attention.
References below. Talking commercial programmers
Ed
By Anthony C Date 2008-02-04 14:47 The true inventor of LMR was Stefan Meyer-Kahlen, of course, which is why S7-S9 completely dominated the computer chess world. But Fabien gets credit because he published his work. Stefan didn't, and random message board discussions certainly do not count.
...
cheers,
anthony
and:
By Vasik Rajlich Date 2008-02-08 09:35 Actually, I talked to Stefan about it and yes, he was using LMR in almost exactly the modern way already with Shredder 7. This means re-searches, exceptions for late-move captures and other special moves, etc.
In my view, Tord clearly deserves the main credit for LMR. Fabien probably deserves the #2 spot, since Fruit is what really showed beyond any doubt that this works.
Vas