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Subject: Re: Asymmetry in Genius?

Author: Thorsten Czub

Date: 08:08:35 09/15/05

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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



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