Author: Dieter Buerssner
Date: 16:15:08 09/29/01
Go up one level in this thread
On September 28, 2001 at 17:48:19, Uri Blass wrote:
>On September 28, 2001 at 17:23:37, Dieter Buerssner wrote:
>> 79835250 23:46.9 0.47 24. 1.c4 Kb7 2.a4 Kc6 3.Kg5 Kc7 4.Kf6 Kd7 5.a5 Kd6
>> 6.Kf5 Kc7 7.Ke6 Kc6 8.Ke7 Kc7 {HT} {0}
>>
>>>Pawn endings are difficult!
>>
>>I won't disagree at all.
>>
>>Regards,
>>Dieter
>
>Note that I suspect that yace may find a forced mate after 8...Kc7
Unfortunately, this is a bit too optimistic ...
Yace did not find the forced mate after Kc7 within 5 minutes with my
configuration (hardware, TBs, hash ...).
>After 9.Ke8 Kc8 the top programs have no problem to see a forced mate.
>I expect yace to be sligthly better and to see a forced mate even without 9.Ke8
>Kc8
After Kc8, there is no problem, to see a mate in 25. But after 9...Kc6 it was
much more difficult to see a mate. Yace can see a very high score soon, but no
mate. There are various reasons. In this line, it seems to be easier to avoid a
mate from KPPKP, the only relevant 5-men TB I have installed. I can see lines,
that end in 5-men positions, and are obviously won, but I don't have the
relevant TBs (that are almost totally useless for normal playing in my opinion -
KQQKP etc). Also, the first mate I have seen was a forced TB mate, where the
transition to TBs was rather deep (after whites 25th move).
I have followed the suggested moves in analyze mode, until a mate score was
seen. I have undone the moves. Following the above line from back to front, I
get (note, that many moves are from HTs, and may not be correct, the scores
should be correct upperbound scores for black and lower score bounds for white):
7625631 46.846 Mat30 21t 9.Ke8 Kc6 10.Kd8H bxa5H 11.Ke7H Kc7H 12.Ke6H
Kc6H 13.Ke5H Kb7H 14.Kd6H Kb6H 15.b4H cxb4H
16.Kd5H a4H {HT} {-160}
Backing up further:
5456871 28.241 Mat33 14t 6.Kf5 Kc7 7.Ke6H Kc6H 8.Ke7H Kc7H 9.Ke8H Kc6H
10.Kd8H bxa5H 11.Ke7H Kc7H 12.Ke6H Kc6H 13.Ke5H
Kc7H 14.Kd5H Kb6H 15.Kd6H {HT} {-80}
And (still the first moves are the same as above):
1582424 13.502 Mat35 16t 4.Kf6 Kd7 5.a5H Kd6H 6.Kf5H Kc7H 7.Ke6H Kc6H
8.Ke7H Kc7H 9.Ke8H Kc6H 10.Kd8H bxa5H 11.Ke7H
Kc7H 12.Ke6H Kc6H 13.Ke5H Kc7H 14.Kd5H Kb6H
15.Kd6H Kb7H 16.Kxc5H Kc7H 17.Kd5H Kd7H {HT} {0}
After this I lost the patience, to want to prove a mate. When I back up further
until the initial position, I get a winning score for white:
9441731 1:20.3 12.62 19. 1.c4 a5 2.a4 Kb7 3.Kh6 Kc8 4.Kg6 Kd8 5.Kf6 Ke8
6.Ke6 Kf8 7.Kd5 Kg7 8.Kc6 b5 9.Kxb5 Kh7 10.Kxc5
Kh6 11.b4 Kg6 {HT} {160}
Of course, the PV may look stupid now. The reason is, that in the "real" PV,
already a mate was proven, and now this mate is avoided. Most probably, 1...a5
will yield in a shorter mate.
Regards,
Dieter
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