Author: Vincent Lejeune
Date: 13:11:10 04/01/00
Go up one level in this thread
On April 01, 2000 at 12:02:06, blass uri wrote: >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 Sorry, I was not completely awake when I read your message. My mistake ... Vincent
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