Author: Heiner Marxen
Date: 14:09:35 05/04/01
Go up one level in this thread
On May 04, 2001 at 16:05:36, leonid wrote:
>On May 04, 2001 at 15:38:23, Angrim wrote:
>
>>On May 04, 2001 at 10:26:02, leonid wrote:
>>
>>>Hello!
>>>
>>>Had bad lack this midnight when one call came from my work. It took me 20
>>>minutes to do it but I went to my bed only at 2 o'clock. One good result from
>>>broken sleep was this position that you can try to solve. It probably will
>>>demand one sleepless night from your program, if you will insist on shortest
>>>mate.
>>>
>>>[D]RnqkqnR1/qBNbNBq1/QqQqQqQ1/BrQqQrB1/3q4/8/3Q4/3K4 w- -
>>>
>>>Please indicate your result.
>>>
>>>Thanks,
>>>Leonid.
>>
>>this one IS tough,
Chest agrees: there is no mate in 12, as found in 2.1 hours (K7/600, 350MB).
>> wonder if having endgame tables would help a lot?
>
>Never!
:-) :-)
There are 16+15 = 31 men on the board. A mate in 12 is 23 plies deep,
so we are left with 31-23 = 8 men at least for a terminal position in
such a search. You have to go some moves deeper before there is a chance
that 6-piece tables may help.
>>I'll leave my proof number searcher running while I'm at work, maybe it
>>will find an answer in a few hours.. currently its obsessing over Qxd7.
>
>Everything depend on each program branching factor. Two professional that I
>tried until now (they are not specialized in solving mate nut never hung on you)
>were slow. The every next program could have very good branching factor for this
>position. I had the chance to see very good on mine, mainly for brute force.
>Selective was slow. It took this in 10 min 42 sec. Celeron 600Mhz. No hash.
>
>Leonid.
Well, the effective branching factor is quite good for Chest.
Here is the timing for the increasing depths:
seconds
# 1 0.00 0.87 1- 0
# 2 0.00 1.00 1- 0
# 3 0.00 0.95 70- 0
# 4 0.08 1.07 465- 0
# 5 0.37 1.27 2085- 0
# 6 1.46 1.57 7901- 0
# 7 6.32 2.09 34402- 0
# 8 25.78 2.57 141569- 0
# 9 87.41 3.28 500658- 0
# 10 478.70 3.56 2712514- 478
# 11 1570.93 4.26 8976242- 1058845
# 12 7659.24 3.73 44489747- 35741846
depth 7-> 8: 4.079
depth 8-> 9: 3.390
depth 9->10: 5.476
depth 10->11: 3.281
depth 11->12: 4.875
It changes a bit up and down, but stays between 3 and 5.5 so far, which
is not bad for such a crowded board and 69 initial legal moves.
But no cigar, yet.
>>proven that lots of the other moves lose already though.
>>proved that 26 of the other moves lose after 10 minutes search..
>>
>>Angrim
Yes, for (nearly) all partial mate-in-3 Chest tried to mate the attacker
directly in 1 move, which succeeded in 16.2% of the cases. A more
sophisticated heuristic might succeed in many more cases.
Now, Leonid, should I go on? Depth 13 and 14 will take around 9 hours
and 1.5 days! What is your shortest (selective) solution?
Cheers,
Heiner
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