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Subject: Re: Asymmetry in Genius?

Author: Mike Byrne

Date: 11:47:16 09/15/05

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On September 15, 2005 at 11:08:35, Thorsten Czub wrote:

>try out the following position:
>
>http://www.thorstenczub.de/Txe6.jpg
>
>genius has problems finding 1.Rxe6 (and later Rxg6)
>this is because the key moves are in 1 and 3 ply.
>
>if genius would search them in ply 2 and 4 it would easily see it.
>
>you don't believe it ?
>
>try out the position one move before with black to move
>
>http://www.thorstenczub.de/einenvorTxe6.jpg
>
>and you see that 1. Rc8 Rxe6 Ra7 Rxg6+ fxg6 appears in an instant.
>
>genius search is pruning more in the own plies and following almost all moves in
>the opponent plies.
>
>therefore it cannot find the solution here when it has white, but would see it
>as
>thread against itself if you take back one move and let it compute as black.
>
>this is also the reason genius plays very defensive, because it sees all threads
>against itself but not all good moves for itself.
>
>this helped genius dominate the computerchess scene for a long time.
>but when nullmove was used in computerchess, the asymetric search suddenly was
>not the one with the fastest tree anymore. therefore there was no advantage
>anymore and genius was not anymore number one.
>
>in all richard lang programs this method has never changed.
>
>its in the amsterdam module, in the roma, in the vancouver, in the genius
>1,2,3,... 7.1 and in the mobile versions.
>
>he never changed this.
>and so the programs strength never changed much.
>
>
>
>
>all written on my website, sorry that it is in german...
>
>http://www.thorstenczub.de/antichrist.html

it also makes it a tough opponent for humans - very nice program, for along time
, it was king of the hill



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