Author: leonid
Date: 14:06:44 01/19/01
Go up one level in this thread
On January 19, 2001 at 15:32:49, Heiner Marxen wrote:
>On January 18, 2001 at 22:06:37, leonid wrote:
>
>>On January 18, 2001 at 19:13:22, Paul wrote:
>>
>>>On January 18, 2001 at 19:01:08, Pete Galati wrote:
>>>
>>>>On January 18, 2001 at 18:44:05, leonid wrote:
>>>>
>>>>>Hi!
>>>>>
>>>>>If you would like to find a mate here is one position. It is very easy to solve
>>>>>but not that simple to find shortest mate.
>>>>>
>>>>>I failed here even in 3 hours to find shortest mate through brute force search.
>>>>>Maybe you will have better chance.
>>>>>
>>>>> 1k4q1/1pppPr2/PbbP1N1n/QP2rn1R/1q6/1q2RBB1/q1q2PPP/6NK black to go
>>>>>
>>>>>Leonid.
>>>>
>>>>Is this the right position?
>>>>
>>>>[D]1k4q1/1pppPr2/PbbP1N1n/QP2rn1R/1q6/1q2RBB1/q1q2PPP/6NK b - - 0 1
>>>
>>>If so, then mine says it's a mate in 10 for black starting with Nxg3+ ...
>>>It looks like a daily reverse auction ... Anyone lower, anyone? :)
>>>
>>>Paul
>>
>>Position is exact and response 10 moves must be or shortest possible, or very
>>close move. Actually my program solved this position through selective search in
>>11 moves. Solution was instant. Finding shortest mate is the other story.
>>Through brute force program said in 8 mate is not there. Only 9 still could be
>>looked.
>>
>>I found that branching factor was terrible to see 9 moves. AMD 400Mhz.
>>
>>8 moves - 2h 44 min.
>>7 moves - 2 min 48 sec.
>>6 moves - 7 sec.
>>
>>Leonid.
>
>Now, with the correct side to move, Chest has still found "no mate in 9".
>But the timing indicate an unusually large branching factor:
># 1 0.00 0.87 1- 0
># 2 0.01 1.00 1- 0
># 3 0.02 0.96 89- 0
># 4 0.06 1.09 437- 0
># 5 0.27 1.30 1693- 0
># 6 2.04 1.38 6662- 0
># 7 31.09 1.49 63238- 0
># 8 824.56 1.75 1256916- 3
># 9 24061.56 2.19 37677207- 28929306
>(depth, seconds, speed, nodes in-out) on a K7/600 (350 MB TT)
>
>That are already 6.7 hours. I'm not sure I will wait until the mate in 10
>arrives. We can expect over 8 days from the above data. The last two
>lines have indicate an effective branching factor of 29.2.
>Although this is a bit better than Leonid's factor 60, it is still quite
>a bit too heavy.
>
>Heiner
So it was really 10 moves positions!
Your branching factor is much better that mine. Only position? Better move
ordering? I don't know. It could be even hash table. And how after your
experience hash helps in branching factor? If there ever existe some difference
at all.
Can see that in general our branching factor have the same tendency for this
position. It grows to the worst with the number of plys to be seen. In mine it
goes this way:
4 moves - 0.1 sec
branching = 8.8
5 moves - 0.88 sec
branching = 8.2
6 moves - 7.25
branching = 23
7 moves - 2 min 47 sec
branching = 59
8 moves - 2 h 43 min 56 sec
Leonid.
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