Author: Michael Borgstaedt (GOLIATH CHESS)
Date: 06:22:15 11/26/01
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On November 26, 2001 at 07:56:42, Steve Maughan wrote: >Uri, > >Please note I'm not critisising Goliath just using it as an example of a fast >nodes / second engine. > >>What do you mean by piece-table evaluation? > >The normal definition e.g. a knight on e5 always gets +350 from a pre-computed >table > >>Goliath does not use piece-table evaluation > >I'd be amazed if it didn't. The nodes / second are too high for it to be >spending any significant time in the evaluation function. I guess it's possible >that Goliath doesn't have the definition of nodes / second. > >>you cannot evaluate passed pawn only by piece square table and it seems that >>goliath knows to evaluate passed pawns and here is the proof: >> >>goliath can see positive score for white inspite of the fact that it does not >>see the promotion >> >>Goliath Light 1.5 - Blass,U >>7k/7r/2pp4/2p5/2p5/8/PK6/7R w - - 0 1 > >The example shows that Goliath does know about passed pawns and the squared rule >for them being unstoppable. In this sense you're right it isn't a *pure* piece >square table engine. However from the n/s I believe that it must be mainly >piece square table based. The example you give could be solved using a simple >pawn hash - so I guess that Goliath does a leaf evaluation of pawns coupled with >piece square tables for the other pieces. > >>How do you know this information about goliath and chessmaster? >>The source code of Goliath or Chessmaster is not free so the only way that you >>can know is if you talk with the programmers. > >Frans Morsch in London 2000 said that Chessmaster evaluated the control of each >square - I don't know from where he found this. As regards Goliath, I'm >assumming from the nodes / second. > >Regards, > >Steve Less than 5% of the evaluation in Goliath (Light 1.5) is done by "piece-table evaluation". Besides, nearly no prescanning is done. The latest version (which won the blitz tournament during the WM/Maastricht) comes without any type of prescanning or piece-table evaluation. Little/Light Goliath uses much (!) more chess knowledge than many users would expect. But Goliath is still extremely fast and the only "secret" is the way, how I realized the cooperation between search and knowledge. This has nothing to do with "lazy evaluation". Goliath uses a special "oracle" which decides, how much and what type of knowledge will be used for the reached leaf position. And, of course, the essential parts of the program (search, make/unmake move and so on) are highly optimized for speed. Michael
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