Author: William Bryant
Date: 13:56:13 07/30/99
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On July 30, 1999 at 16:21:56, Terry Ripple wrote: > A friend of mine who has a rating of USCF 2345 asked me that in order for your >favorite chess program to do a 9 ply search, how many moves or positions are >there on the chess board that it would need to search in order to accomplish >this goal? > I hope i`am getting my point across to what i`am trying to ask for! It just >seems that the numbers to do such a task would be in the billions for a complete >search of 9 ply! > Plus, they talk alot about how many Nodes per second a program can do and is >there a formula to find out how many moves or positions your favorite program >can do in relation to the KN/s? > >Thankyou in advance for any help in explaining this, >Best regards, >Terry There isn't an absolute number of positions or nodes that need to be checked and a simple response would be "enough to get the right move" :)))) Different programs will produce different node counts for the same search depending upon the programs selectivity and the pruning of the search. For example, I have done very little since adding attack tables to improve the overall speed of my program in the last 3 to 4 months. I'm still running at about 50k NPS in the early middle game. But, the time to get from 0 to 10 plies has dropped significantly associated with more selectivity in the search. In other words the number of nodes that I have searched in order to complete 9 plies has dropped significantly. The most recent change (that may still have a bug or three) was to add a static exchanage evaluator and Q-search delta pruning. By this, I mean that I am dropping all captures that don't restore the material score back close to alpha (ala Crafty -- Thanks Bob). This has cut the time it takes me to reach ply ten from the starting prosition of 1.e4 from 2:13 to 1:13 -- almost a 50% time increase. This means that I have cut the nodes I have searched by almost 50%. I bet if you look all the top programs, the nodes to achieve ply 9 from any given position will vary, possibly by a large number. Hope this helps. William wbryant@ix.netcom.com
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