Author: Heiner Marxen
Date: 03:19:35 02/03/02
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On February 02, 2002 at 07:37:27, leonid wrote: >[D]2QqQN2/1q3q1R/B1r1RPq1/n1k2N1q/Rq1rq1bP/1Q2P1B1/2q2b1q/K2nB3 w - - > >Please indicate your result. > >Thanks, >Leonid. Hello Leonid, This one is surprisingly accessible for Chest: on my Athlon/600 with 350 MB hash it needs only 65.8 minutes to find that this is a mate in 12 with two key moves: PV: Bxb4+ Qxb4 Re5+ Qed5 Nd7+ Qdxd7 Qf8+ Qxf8 Qxf8+ Rd6 Rxd5+ Kc6 Bb7+ Kxb7 Rxd7+ Qc7 Rxb4+ Rxb4 Qxb4+ Rb6 Rxc7+ Ka6 Rxa5# PV: Re5+ Qed5 Nd7+ Qdxd7 Bxb4+ Qxb4 Qf8+ Qxf8 Qxf8+ Rd6 Rxd5+ Kc6 Bb7+ Kxb7 Rxd7+ Qc7 Rxb4+ Rxb4 Qxb4+ Rb6 Rxc7+ Ka6 Rxa5# After the first 3 moves both transpose to the same position/solution. The timing shows a very good EBF: it is shrinking all the time down to below 3: # 3 0.01s 1kN [ 14.57] 0.96 62- 0 # 4 0.11s [ 11.00] 7kN [ 8.14] 1.10 483- 0 # 5 0.46s [ 4.18] 35kN [ 5.23] 1.43 2129- 0 # 6 2.41s [ 5.24] 159kN [ 4.58] 2.07 11344- 0 # 7 9.97s [ 4.14] 618kN [ 3.89] 3.39 49756- 0 # 8 38.48s [ 3.86] 2275kN [ 3.68] 5.23 203391- 0 # 9 113.41s [ 2.95] 6544kN [ 2.88] 8.08 632407- 0 # 10 421.92s [ 3.72] 24007kN [ 3.67] 9.20 2304940- 158 # 11 1426.10s [ 3.38] 77337kN [ 3.22] 10.89 7953425- 564639 # 12 3946.84s [ 2.77] 202561kN [ 2.62] 15.53 24840756- 16092886 Also, the hash table efficiency appears to be better than normally: speed up factor 15.53 for depth=12. This could be the main reason for the small EBF. Finally, in 55.9% of the cases the defender does defend by mating the attacker in just 1 move, cutting off the search tree. Cheers, Heiner
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