Author: Christophe Theron
Date: 13:06:11 03/19/98
Go up one level in this thread
On March 19, 1998 at 11:45:39, Ernst A. Heinz wrote:
>On March 19, 1998 at 11:11:25, Christophe Theron wrote:
>
>>On March 19, 1998 at 04:25:22, Ernst A. Heinz wrote:
>>
>>>
>>>"DarkThought" is an aggressive null move searcher and finds 1. Rd1+!
>>>in iteration #2 after just 464 nodes.
>>>
>>>It returns the mate score in iteration #8 after 4380 nodes.
>>>
>>>=Ernst=
>>
>>Well done!
>>
>>Note that what is interesting is not when the key move is found (it can
>>be found by pure luck), but when the program announces mate.
>
>No luck involved here because "DarkThought" scores the position as >=
>-1.5
>from iteration #2 onward.
>
>> Being an "agressive" null mover, DarkThought sure has a good zugzwang
>>detection scheme. I suppose you don't just turn null move off when there
>>is only one piece left? It would be very ineffective in most endgames...
>>Especially rook endgames.
>
>As reported in my ICCA Journal 20(3) article "DarkThought" performs
>recursive null moves until one side has no more pieces, i.e., it still
>does null moves in minor piece endgames with one piece per side. It
>does not use a special Zugzwang detection scheme but instead relies on
>its extensions and high search depths to overcome Zugzwang glitches.
>
>=Ernst=
So it should never find the solution of the given position. I am curious
to know how you explain this miracle...
The problem with zugzwang is that it doesn't add more plies to find the
solution in this case. It is that if you fail to detect it and keep on
using null move, you simply NEVER find the solution...
Christophe
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