Author: Christophe Theron
Date: 21:56:56 07/20/99
Go up one level in this thread
On July 20, 1999 at 18:52:52, Albert Silver wrote:
>On July 19, 1999 at 15:34:34, Tania Devora wrote:
>
>>
>>
>>Sorry the las positions is this :
>>
>>
>>White : Ra2. Kc8.
>>pawns : b6.
>>
>>
>>Black : Ka8. Bb8
>>Pawns : b7. a6.
>>
>>
>>
>>Fritz cant see a simple MATE IN TWO !!
>>
>>Hiarcs cant see in less than a second!
>
>Tania, if this is really supposed to be a mate in two, then the only thing I can
>think of is the Black pawns should be on b7 and a7 (as opposed to a6).
>
>kbK5/pp6/1P6/8/8/8/R7/8 w - - 0 1
>
>In that case, White would have the straightforward Ra6 which the programs should
>hit on instantly.
No they don't because of the null move algorithm.
>If the Black a-pawn is indeed on a6:
>
>kbK5/1p6/pP6/8/8/8/R7/8 w - - 0 1
>
>then the mate will take a few moves more.
>
> Albert Silver
Some programs don't see the mate in 2 (with both pawns on the 7th rank) because
after 1. Ra6! black is in zugzwang.
Looks like nobody has read my previous post and I'm just losing my time trying
to explain it...
Both Hiarcs and Fritz would fail on some zugzwang positions. Not on this one,
which is solved by Hiarcs, but there are positions where Hiarcs fails completely
because of its null move algorithm.
...OK, just losing my time... :)
Christophe
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