Author: Chris Whittington
Date: 14:58:22 12/26/97
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On December 26, 1997 at 14:16:30, Thorsten Czub wrote: >>Perhaps they are doing heavy pruning on the computers moves? If you >>modify the selectivity such that much heavier pruning takes place >>on the computers side you might arrarnge extra depth that results in >>play that is safe but not opportunistic for the computer. > > >Right. Pruning is ONE explanation. > > >>I remember Richard Langs programs USED to have the characteristic >>that they would see anything you could do to them. In some experiments >>me and Larry Kaufman did, it would quickly see that you could win >>a piece and avoid the loss. But if you forced the piece losing move >>and let it think for the winning side, it could not find the win without >>a very long think! Very strange. But this was the best program in the >>world and pehaps still is. > >Exactly. But Richard did it with asymmetrie. >The plies 1,3,5,7,9,... were very much pruned and genius followed only >the best 4 or 5 branches and the moves 2,4,6,8,... were looked >brute-force. >This gave him some extra plies and more look-ahead than his opponent >programs at this time. >With the invention of null-move his advantage was melted because the >null-move algorithm was as effective as his asymmetrie ! Also his >assymmetrrie caused boring style due to the fact that genius played in >the plies 1,3,5,7,... often NOT THE BEST move. Yup, his pruning was by 'interest'. He only extended his lines if they were active, or threatening, or whatever. This required intelligence at each node for forward pruning/extending. So Genius searched his opponent fully, but himself only on active lines. Therefore he could find good attacks, but not good maneouvers. This used to work when the opponents were semi-full-width on both odd and even plies without compensationg advantages. Now the have the compensation. Chris Whittington >> >>But this makes some sense to me. I don't think a single chess game has >>ever been won without an error on the losing side. If your program >>NEVER made an error (you wish!) it would never lose (unless of course >>the opening position is a loss for one side or the other.) >> >>I have known people who play like this too. They would be paranoid >>about their half of the board and never take even slight risks for >>a chance to win. Often these players did quite well although they >>played boring chess. I've even seen their opponents walk away in >>disgust! But these players often got very good results. It's >>up to their opponents to prove there is something wrong with this >>style. > >Right. > >I am looking forward to study Junior ! Hi Amir ! We will find it out !! >:-) > > >> >> >>-- Don
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