Author: Heiner Marxen
Date: 12:32:49 01/19/01
Go up one level in this thread
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
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