Author: Uri Blass
Date: 02:28:39 12/03/01
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On December 03, 2001 at 04:34:03, Gian-Carlo Pascutto wrote: >On December 03, 2001 at 03:55:56, Uri Blass wrote: > >>I do not understand it and I will be happy to see an example of a tree >>that leads to pruning the main line. > >It should happen in any branch where there was some form >of forward pruning leading to a lower bound on the score, >and where the branch was researched later on. > >There are probably other cases, but this is the obvious >example. I still prefer to see an example to understand and it means a chess position and the nodes that the program searches before showing the wrong line. I do not understand much about the search of chess programs. The following is a summery of what I know about it: I understand the reason for using two bounds alpha beta by the following example that I invented line 1.e4 score 0.1 pawns for white line 1.d4 Nf6 score 0.12 pawns for white line 1.d4 d5 I can have 2 bounds 0.1 and 0.12. If the score for white is less than 0.1 then I know that 1.d4 is illogical(e4 is better and the difference is not important) If the score for white is more than 0.12 then I know that d5 is illogical(Nf6 is better) If the score for white is between 0.1 and 0.12 then the exact score is important for me and I need to calculate it. I also understand the idea of null move pruning that means that you prune moves with no threat when finding if there is a threat is done by searching to reduced depth. > >>I do not agree >>If I analyze a position for many hours for depth 19 and the program found an >>interesting sacrifice then I do not want to analyze also the position after the >>sacrifice for many hours to get depth 18 in order to understand the reason for >>the sacrifice. > >Play out the move. Enough data should still be in the hashtables >that 18 ply can be reached fairly fast. In this case I think that it may be a good idea to do a search for reduced depth for the opponent before pondering because in this way Fritz is not going to ponder for the wrong move. Uri
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