Author: Heiner Marxen
Date: 09:10:46 01/07/05
Go up one level in this thread
On January 07, 2005 at 10:15:06, F. Huber wrote: >On January 07, 2005 at 09:37:55, Heiner Marxen wrote: [...] >> >>Just now I have: >>FEN: 6k1/5Np1/4n3/2Qq2PK/8/8/8/8 w - - >>analysing (mate in 20 moves): >># 1 0.00s 0kN 0.87 1- 0 >># 2 0.00s 0kN 1.00 1- 0 >># 3 0.00s 0kN [ 5.20] 0.92 30- 0 >>% EGTB found tables for max 5 pieces >>% EGTB uses 3728.4K memory internally >># 4 0.02s 0kN [ 3.67] 1.07 117- 0 >># 5 0.02s [ 1.00] 2kN [ 3.82] 1.51 317- 0 >># 6 0.07s [ 3.50] 11kN [ 6.22] 1.82 1444- 0 >># 7 0.23s [ 3.29] 51kN [ 4.51] 2.34 5591- 0 >># 8 0.94s [ 4.09] 243kN [ 4.76] 2.90 22069- 0 >># 9 3.07s [ 3.27] 726kN [ 2.98] 3.31 70315- 0 >># 10 6.83s [ 2.22] 1559kN [ 2.15] 4.02 155844- 1 >># 11 20.39s [ 2.99] 4502kN [ 2.89] 4.74 429776- 12 >># 12 64.43s [ 3.16] 13345kN [ 2.96] 6.58 1143927- 2685 >># 13 244.35s [ 3.79] 48544kN [ 3.64] 8.60 3750376- 1285851 >># 14 889.90s [ 3.64] 179343kN [ 3.69] 9.96 13432518- 10933117 >># 15 3422.06s [ 3.85] 670844kN [ 3.74] 12.51 47288122- 44788721 >># 16 14485.35s [ 4.23] 2862927kN [ 4.27] 12.36 193945070- 191445669 >># 17 59920.91s [ 4.14] 12006250kN [ 4.19] 12.45 801825148- 799325747 >> [...] >>Obviously, the branching factor causes the slowness (not vice versa). >>And Chest's worse branching factor most probably is due to its selection >>of defender moves. While Chest is not naive about this, it is far from >>perfect, and sometimes a bit of "luck" is involved, also. >> >>For a more detailed explanation we had to compare the search trees of >>Chest and Gustav in more detail. >> >>But when Gustav's branching factor here is as good as 2.5 there should >>be a good chance to have Gustav complete depth 20, right? Have you tried? > >Hello Heiner, Hello Franz, >no, I didn´t try it - if you remember, I´m usually working on a slow Celeron/400 >and it needed already 3 1/2 min to finish depth 13! >So if I extrapolate the factor 2.5 for another 7 moves, this will take about >1 1/2 days - I doubt my more than 5 years old notebook will bear this torture! >:-( > >Sorry that you had no luck with this KNPKP file, but since I´m quite sure that >this position is indeed only a mate in 20, I´d guess that even this file won´t >be of much use for a brute force search - if there really exists a shorter mate, >then certainly not with only those 5 pieces. > >But I think this special position isn´t really interesting for mate solving, >so we shouldn´t waste more of our time with it ... ;-) Ok, you are right. The next line (depth 18) would have needed days already (factor >4), so I killed the job. >Regards, >Franz. Cheers, Heiner
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