Author: blass uri
Date: 09:02:06 04/01/00
Go up one level in this thread
On April 01, 2000 at 11:49:01, Vincent Lejeune wrote: >On April 01, 2000 at 10:32:52, blass uri wrote: > >>On March 31, 2000 at 23:17:45, Robert Hyatt wrote: >> >>>On March 31, 2000 at 12:53:43, Stephen Ham wrote: >>> >>>>Dear Readers, >>>> >>>>I know many of you are actively following my ongoing match games versus Fritz 6a >>>>and Nimzo 7.32. For those of you not familiar with the event, please visit: >>>> >>>>http://correspondencechess.com/campbell/index.htm >>>> >>>>Anyway, a frequent poster here (name is withheld) wrote to Mr. Campbell stating >>>>that since the chess engines are displaying their top 3 choices, they are being >>>>weakened "a lot". No explanation was given for that claim. >>>> >>>>Would somebody here please provide a detailed explanation regarding whether this >>>>claim is correct and why? >>> >>> >>>It depends on how they compute these variations. Done correctly, it is >>>_horribly_ inefficient. If you watch a normal search, the first move will >>>usually take over 50% of the total time. The remaining N-1 moves take the >>>remaining 50% of the time. If you have it display two 'best'moves, you >>>increase the total search time by roughly 50%. The first move takes the >>>same time as before. The second move also takes the same time as before, >>>and the final N-2 moves take just a tad less than before. Net loss is >>>ugly. If you have it display the best 3 moves, you slow it down by exactly >>>a factor of two... >>> >>> >>> >>> >>>> >>>>The chess engines are on settings recommended by ChessBase USA as their optimal >>>>settings for this event. My extremly limited understanding is that displaying >>>>the top 3 choices does indeed affect the chess engines, but it causes them to >>>>spend more time on what it believes to be the 3 best moves. As such, this sounds >>>>like an enhancement to me. Given that the chess engines are allowed about 24 >>>>hours calculation time on weekdays and are searching to 16-18 ply, I can't >>>>imagine that this weakens them in any way. >>> >>> >>>Each iteration will take about 2x longer than the previous. Rather than >>>a branching factor of 3x, you raise it to 6x. This will cost several plies >>>over 24 hours. >> >>My experience with chessbase engines show that it is not the case. >>I also see no reason that the branching factor will change. >> >>The program is going to be slower by a constant factor by calculating the first >>3 moves. >>The only difference relative to calculating only the best move is that you need >>to use time to calculate the second best move and the third best moveand I do >>not see a reason to be more than 3 times slower. >> >>The only case when the branching factor is going to be bigger is if you generate >>a tree of moves and not only the best 3 moves. >> >>Uri > >I think you're wrong : check depth after 1 minute with 1st best move and once >again with 5 best moves, my Hiracs 7.32 clearly slows ... I did not say that the depth is the same but that the branching factor is the same. The question if time for depth 10 divided by time for depth 9 is bigger when you use 5 options. Uri
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