Author: Heiner Marxen
Date: 11:50:32 12/26/02
Go up one level in this thread
On December 26, 2002 at 04:29:01, Uri Blass wrote: >On December 25, 2002 at 23:23:48, Drexel,Michael wrote: > >>[D] Q2Q2Q1/1R6/3BR3/3k3N/2RB2Q1/5R2/Q2Q2Bp/3N3K w - - 0 1 >> >>Problem: >>White to move >>If white gives check it has to be mate in one. >>Find a legal position with the highest number of possible checks. >> >>I discovered this 5 years ago. Took me about 16 hours to find it. >>I think it is possible to find a proof that it is not possible to find more: >> >>85 mates in one! :-) >> >>I must have been crazy. >> >>Fritz 7.0.0.8 engine crashed in Analysis mode if I increase the number of lines >>to 64 (maximum). Shredder 7 not. >>I have checked it under Fritz 7 GUI and Shredder7 (=Fritz8)GUI. > >perft 1=142 >perft 2=12 >perft 3=1603 >perft 4=415 >perft 5=53576 >perft 6=45655(0.12 seconds) >perft 7=5844247(movei optimized for perft 0.431 seconds)(yace 1.054 >seconds)(movei normal version for today 0.491 seconds) >perft 8=3651048(13.139 seconds)(yace 23.774 seconds)(movei normal version for >today 13.5 seconds) >perft 9=441,943,521(37.504 seconds)(yace 90.728 seconds)(movei normal version >42.271) Chest agrees completely: FEN: Q2Q2Q1/1R6/3BR3/3k3N/2RB2Q1/5R2/Q2Q2Bp/3N3K w - - Counting width of legal tree, 9 plies deep... Time (user) = 35.41 sec dep #nodes quot sum nodes 0 1 [ 0.000] 1 1 142 [142.000] 143 2 12 [ 0.085] 155 3 1603 [133.583] 1758 4 415 [ 0.259] 2173 5 53576 [129.099] 55749 6 45655 [ 0.852] 101404 7 5844247 [128.009] 5945651 8 3651048 [ 0.625] 9596699 9 441943521 [121.046] 451540220 (Athlon 1500+) >perft 10=950,008,655(1031.73 seconds) >The last number was not verified by other programs. > >Finally we get perft 10>perft 9 > >The surprising fact in these results is that >perft 8/perft 7<perft 6/perft 5 and >perft 4/perft 3<perft 6/perft 5. > >I give another challange > >Find the biggest number n such that perft(n)=0 and perft(n-1) >0 > >here is a simple example that proves that n>11 > >[D]k1q5/P2QQQQQ/KP6/PP6/4q3/5q2/6q1/7q w - - 0 1 > >perft 1=3 >perft 2=4 >perft 3=4 >perft 4=6 >perft 5=6 >perft 6=8 >perft 7=8 >perft 8=10 >perft 9=10 >perft 10=10 >perft 11=5 >perft 12=0 Again, Chest agrees. >It is also easy to see that n>12 by the following example > >[D]k1R5/P2QQQQQ/KP6/PP6/4q3/5q2/6q1/2q4q b - - 0 1 > >Uri Just one ply deeper: FEN: k1R5/P2QQQQQ/KP6/PP6/4q3/5q2/6q1/2q4q b - - Counting width of legal tree, 14 plies deep... Time (user) = 0.00 sec dep #nodes quot sum nodes 0 1 [ 0.000] 1 1 1 [ 1.000] 2 2 3 [ 3.000] 5 3 4 [ 1.333] 9 4 4 [ 1.000] 13 5 6 [ 1.500] 19 6 6 [ 1.000] 25 7 8 [ 1.333] 33 8 8 [ 1.000] 41 9 10 [ 1.250] 51 10 10 [ 1.000] 61 11 10 [ 1.000] 71 12 5 [ 0.500] 76 Cheers, Heiner
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