Author: Dieter Buerssner
Date: 01:43:00 05/22/05
Go up one level in this thread
On May 22, 2005 at 03:32:52, Helmut Conrady wrote:
>On May 21, 2005 at 19:58:41, John Merlino wrote:
>
>>On May 21, 2005 at 17:50:19, Dieter Buerssner wrote:
>>
>>>On May 21, 2005 at 17:42:40, John Merlino wrote:
>>>
>>>>On May 21, 2005 at 11:16:37, Steven Edwards wrote:
>>>>
>>>>>On May 21, 2005 at 10:54:12, David Dahlem wrote:
>>>>>
>>>>>>What's the shortest forced mate from this position, and can any engine find it
>>>>>>without tablebases?
>>>>>>
>>>>>>2KB4/1P6/2k5/8/8/8/7b/8 w - - 0 1
>>>>>
>>>Yace confirms this. The PV may give little bit more information:
>>>
>>> 1...Kb6 {EGTB} 2.Bf2+! Ka6! 3.Bc5! Bg3 4.Be7!
>>> Kb6 5.Bd8+! Kc6! 6.Bh4! Bf4 7.Bf2! Bd6 8.Ba7!
>>> Be5! 9.Bb8! Bd4! 10.Bc7 Ba7! 11.Bf4 Kd5 12.Be3!
>>> Bxe3! 13.b8=Q!! Bd4 14.Kd7! Be3 15.Qb5+ Bc5
>>> 16.Qe2 Bd4 17.Qe6+! Kc5 18.Qc6+! Kb4 19.Kd6 Ba7
>>> 20.Qb7+ Bb6 21.Qxb6+! Kc3! 22.Qe3+ Kc2 23.Kd5
>>> Kb2 24.Qd2+ Kb3 25.Kc5! Ka3! 26.Kc4! Ka4
>>> 27.Qa2# {-1001}
>>>
>>>! moves for the attacker mean: this is the best move, other moves may win, but
>>>with a longer mate. ! moves for the defender: all other moves will allow shorter
>>>mate for the attacker. !! move for the attacker: only move, that wins (any other
>>>move will draw ór lose).
>>I gotta admit I love that feature of Yace. :-)
>I agree! :-)
>
>BTW: Shredder can do the same, too.
Helmut, which version of Shredder? It seems my versions cannot do it (at least
not in normal search/analysis mode). Actually Yace cannot really do it when
running under the Shredder GUI. The GUI can only display about 27 half moves of
the PV. For the PV, I know of no way to display the !/!!. For this reason, Yace
sends the PV again as formated string. But Shredder will in general also cut
this string before the mate is reached. Note, that the feature may be more
interesting, when the root position is not inside TBs yet, where endgame oracle
features will not work, but still a forced mate may be found, that transposes
some moves later into TBs.
Regards,
Dieter
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