Author: Uri Blass
Date: 01:12:41 03/18/01
Go up one level in this thread
On March 17, 2001 at 23:37:06, Dieter Buerssner wrote:
>On March 17, 2001 at 21:18:35, Robert Hyatt wrote:
>
>>On March 17, 2001 at 10:22:39, Dieter Buerssner wrote:
>>
>>>On March 17, 2001 at 06:13:23, Christian Koch wrote:
>>>
>>>> 8/8/pq1PQ1kp/6p1/8/7P/5PK1/8 b - -
>>>>
>>>>This is the evaluation of Gandalf. Gandalf needs much time to see that he is
>>>>totally lost. Other programms only need seconds to see it.
>>>>I think Gandalfs endgame should be improved to play at a high level.
>>>
>>>I tried this position with Yace. Something strange happened:
>>>
>>> 51305 0.702 -0.40 5. 1...Kg7 2.Qe7+ Kg6 3.Qe8+ Kf6 4.Qe7+ Kg6 5.Qe8+
>>> Kf6 6.Qe7+ Kg6 {0}
>>> 111931 1.638 -0.80 6-- 1...Kg7 2.Qe7+ Kg8 3.d7 Qc6+ 4.Kg3 Qc7+ 5.Kg4
>>> Qc6 6.d8=Q+ Qe8 {-921}
>>> 137448 1.868 -7.64 6t 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.d8=Q
>>> Qxh3+ 6.Kg1 {-841}
>>> 150310 1.974 -7.64 6. 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.d8=Q
>>> Qxh3+ 6.Kg1 {-841}
>>>
>>>Here one could assume, that it really sees fast, that black is lost
>>>
>>> 186148 2.222 -7.75 7t 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.Qd6+ Kg7
>>> 6.Qe7+ Kg6 7.Qe4+H Kf7H 8.d8=QH Qxh3+H 9.Kg1H
>>> {-841}
>>> 191019 2.266 -7.75 7. 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.Qd6+ Kg7
>>> 6.Qe7+ Kg6 7.Qe4+ Kf7 8.d8=Q Qxh3+ 9.Kg1 {-841}
>>> 337668 3.199 -7.78 8t 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.Qd6+ Kf7
>>> 6.d8=Q Qxh3+ 7.Kg1 {-841}
>>> 505552 4.276 -7.78 8. 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 g4 5.Qd6+ Kf7
>>> 6.d8=Q Qxh3+ 7.Kg1 {-841}
>>>
>>>And it kept about the same for another 2 plies. But now:
>>>
>>> 1666011 12.245 -7.38 9++ 1...Kg7 2.Qe7+ Kg6 3.Qc7 Qb3 4.d7 Qd5+ 5.Kh2
>>> Qd4 6.d8=R Qxf2+ 7.Kh1 {-340}
>>> 6934801 57.940 -0.40 9t 1...Kg7 2.Qd7+ Kg6 3.h4 {HT}
>>> 7368426 1:01.4 -0.40 9. 1...Kg7 2.Qd7+ Kg6 3.h4
>>>
>>>Huch: we are back at almost drawing score.
>>>
>>> 8889435 1:13.5 -0.80 10-- 1...Kg7 2.Qd7+ Kg6 3.h4 gxh4 4.Qe8+ Kh7 5.Qe7+
>>> Kg6 6.d7 Qc6+ 7.Kh2 Qc7+ 8.Kh3 h5 9.d8=Q a5
>>> {-841}
>>> 12883052 1:46.1 -1.68 10t 1...Kg7 2.Qd7+ Kg6 3.h4 gxh4 4.Qe8+ Kf6 5.d7
>>> Qc6+ 6.Kh2 Qc7+ 7.Kh3 Qc3+ 8.Kxh4 Qc4+ 9.Kg3
>>> Qc7+ 10.f4 Qc3+ 11.Kg4 {HT} {0}
>>> 13257667 1:48.9 -1.68 10. 1...Kg7 2.Qd7+ Kg6 3.h4 gxh4 4.Qe8+ Kf6 5.d7
>>> Qc6+ 6.Kh2 Qc7+ 7.Kh3 Qc3+ 8.Kxh4 Qc4+ 9.Kg3
>>> Qc7+ 10.f4 Qc3+ 11.Kg4 {HT} {0}
>>> 17090908 2:15.6 -2.08 11-- 1...Kg7 2.Qd7+ Kg6 3.h4 gxh4 4.Qe8+ Kf6 5.d7
>>> Qc6+ 6.Kh2 Qc7+ 7.Kh3 Qc3+ 8.Kxh4 Qc4+ 9.Kg3
>>> Qc7+ 10.f4 h5 11.d8=Q+ Kf5 {-921}
>>> 26447712 3:26.8 -6.50 11t 1...Kg7 2.Qd7+ Kg6 3.h4 Kh5 4.Qe8+ Kxh4 5.Qe3
>>> Qxe3 6.fxe3 a5 7.d7 a4 8.d8=Q a3 9.e4 {-841}
>>> 26573747 3:27.8 -6.50 11. 1...Kg7 2.Qd7+ Kg6 3.h4 Kh5 4.Qe8+ Kxh4 5.Qe3
>>> Qxe3 6.fxe3 a5 7.d7 a4 8.d8=Q a3 9.e4 {-841}
>>> 33767907 4:20.6 -6.90 12-- 1...Kg7 2.Qd7+ Kg6 3.h4 Kh5 4.Qe8+ Kxh4 5.Qe3
>>> Qxe3 6.fxe3 a5 7.d7 Kh5 8.d8=Q Kg6
>>>
>>>And after rather long time again at loosing score. I have not investigated the
>>>reasons, but perhaps this is more complicated for a chess program, than it looks
>>>at first sight.
>
>>I would suspect a bug.
>
>That may be the case. And I even suspected this first. But I looked more
>carefully in between. To me it still looks, that at first sight this position
>may seem easier to a program, than after a deeper look. Especially 2. Qe7+ does
>not seem to win fast.
>
>>I ran this and crafty sees +8 instantly and hangs on to
>>that type of score forever.
>
>I actually also had checked Crafty 17.13, and it also showed strange behaviour.
>I Just rechecked with the newest version. It does not really hang at +8. It gets
>one fail high after the other for 1...Kg7, interestingly allways with a
>difference of 0.39, and with exactly the same PV as the previous iteration:
>
> 8-> 1.33 8.05 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. d8=Q Qxf2+ 7.
> Kh1 Kf5 <HT>
> 9 2.30 ++ 1. ... Kg7!!
> 9-> 4.23 7.66 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. d8=Q Qxf2+ 7.
> Kh1 Kf5 8. Qf8+ <HT>
> 10 6.63 ++ 1. ... Kg7!!
> 10-> 11.98 7.27 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. d8=Q Qxf2+ 7.
> Kh1 Kf5 8. Qf8+ <HT>
> 11 18.12 7.61 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. Kg1 g4 7. d8=Q
> Qxd8 8. Qxd8 gxh3
> 11-> 18.27 7.61 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. Kg1 g4 7. d8=Q
> Qxd8 8. Qxd8 gxh3
> 12 1:02 ++ 1. ... Kg7!!
> 12-> 1:42 7.22 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. Kg1 g4 7. d8=Q
> Qxd8 8. Qxd8 gxh3
> 13 2:49 ++ 1. ... Kg7!!
> 13-> 7:54 6.83 1. ... Kg7 2. Qe7+ Kg6 3. Qc7 Qb1 4.
> d7 Qe4+ 5. Kh2 Qd4 6. Kg1 g4 7. d8=Q
> Qxd8 8. Qxd8 gxh3
Crafty18.03 under chessbase(64 mbytes hash) cannot reproduce it.
The score of it is 7.47 at depth 12 but 7.79 at depth 13 when the main line is
1...Kg7 2.Qd7+ at depth>=13
The difference between depthes 11 and 12 is 0.4 pawns and not 0.39 pawns.
At depth 14 the score is +8.02 and it finished depth 14 in a few minutes on
pIII800 that is clearly less than your 20 minutes.
I can reproduce the fail low at depth 9 after Kg7 for Qe7+ and the fail high at
depth 11 for Qd7+
Crafty does not solve the fail high at depth 11 and fail high on Qd7+ again at
depth 12 and it can see +4.67 score at this depth
It fail high again at depth 13 for the same move Qd7+ and solves the fail high
with score 8.66 pawns for white.
I can add that Qe7+ is also an easy win for white when the best line includes a
repetition
1.Qe7+ Kg6 2.Qe6+ Kg7 3.Qd7+
Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.