Author: Heiner Marxen
Date: 12:29:36 07/29/01
Go up one level in this thread
On July 27, 2001 at 21:01:50, Heiner Marxen wrote: >On July 27, 2001 at 19:44:05, Uri Blass wrote: > >>On July 27, 2001 at 19:39:35, Uri Blass wrote: >> >>>On July 27, 2001 at 10:53:28, leonid wrote: >>> >>>>Hi! >>>> >>>>If you are ready, you can solve this problem: >>>> >>>>[D]1N1k1N1B/q1q1q1q1/1rRbRr2/Q1nBn1Q1/1Q3Q2/n1Q1Q1n1/1Q1Q1Q2/n2K2nb w - - >>>> >>>>Please indicate your result... even if your program fail. >>>> >>>>Thanks, >>>>Leonid. >>> >>>chesmaster6000(PIII850 ss=10) >>>solution Rexd6+ >>>3:56 mate in 11 >>>5:47 mate in 10 >> >>and after 10:49 Rxc7 is mate in 9 >> >>Uri > >Chest has "problems" with this problem: to find "no mate in 7" needed already >103 minutes. With an effective branching factor of 15+ the next depth will >need more than a full day. :-( >If there is no mate in 8 it is out of reach for Chest. > >To be continued... :-) > >Heiner Ha! According to Chest this is a mate in 8 :-) But what a huge effort to spend: 162992 sec = 2716.5 min = 45.3 hrs = 1.9 days on a K7/600 with 350 MB hash. For a mate in 8 is kind of a record. PV: Qexc5 Bf3+ Bxf3 Ne4 Rcxd6+ Qed7 Rxd7+ Qgxd7 Bxf6+ Nxf6 Qfxf6+ Kc8 Qd8+ Qxd8 Qgxd8# Surprisingly, the key move is not a checking one. It is a capture move, but it does not even take one of those queens, but rather a knight. :-O Compared with other problems, the effective branching factor is quite bad: depth time EBF[T] EBF[N] hash-factor # 1 0.00s 0kN 0.87 1- 0 # 2 0.00s 0kN 1.00 1- 0 # 3 0.02s 1kN [ 20.33] 0.95 99- 0 # 4 0.61s [ 30.50] 33kN [ 53.84] 1.05 1640- 0 # 5 18.04s [ 29.57] 888kN [ 27.04] 1.23 76121- 0 # 6 359.95s [ 19.95] 17453kN [ 19.66] 1.57 1623694- 16 # 7 6184.85s [ 17.18] 319730kN [ 18.32] 1.94 26133013- 17385126 # 8 162992.70s [ 26.35] 4618561kN [ 14.45] 1.91 673926679- 665178778 Also, the speed up by the hash table could be better. With a recall rate of 7.5% the factor stays below 2. Sort of a "killer problem" for Chest. Wow! Cheers, Heiner
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