Author: Heiner Marxen
Date: 09:08:53 05/05/01
Go up one level in this thread
On May 04, 2001 at 17:09:35, Heiner Marxen wrote: >On May 04, 2001 at 16:05:36, leonid wrote: > >>On May 04, 2001 at 15:38:23, Angrim wrote: >> >>>On May 04, 2001 at 10:26:02, leonid wrote: >>> >>>>Hello! >>>> >>>>Had bad lack this midnight when one call came from my work. It took me 20 >>>>minutes to do it but I went to my bed only at 2 o'clock. One good result from >>>>broken sleep was this position that you can try to solve. It probably will >>>>demand one sleepless night from your program, if you will insist on shortest >>>>mate. >>>> >>>>[D]RnqkqnR1/qBNbNBq1/QqQqQqQ1/BrQqQrB1/3q4/8/3Q4/3K4 w- - >>>> >>>>Please indicate your result. >>>> >>>>Thanks, >>>>Leonid. >>> >>>this one IS tough, > >Chest agrees: there is no mate in 12, as found in 2.1 hours (K7/600, 350MB). > >>> wonder if having endgame tables would help a lot? >> >>Never! > >:-) :-) > >There are 16+15 = 31 men on the board. A mate in 12 is 23 plies deep, >so we are left with 31-23 = 8 men at least for a terminal position in >such a search. You have to go some moves deeper before there is a chance >that 6-piece tables may help. > > >>>I'll leave my proof number searcher running while I'm at work, maybe it >>>will find an answer in a few hours.. currently its obsessing over Qxd7. >> >>Everything depend on each program branching factor. Two professional that I >>tried until now (they are not specialized in solving mate nut never hung on you) >>were slow. The every next program could have very good branching factor for this >>position. I had the chance to see very good on mine, mainly for brute force. >>Selective was slow. It took this in 10 min 42 sec. Celeron 600Mhz. No hash. >> >>Leonid. Chest has just completed depth=13. There are two key moves for the mate in 13: Qexd7+ and Qcxd7+. Here are the PVs: Qcxd7+ Qexd7 Rxf8+ Qxf8 Qxd7+ Qcxd7 Ne6+ Q5xe6 Bxb6+ Rxb6 Qaxb6+ Qaxb6 Rxb8+ Qxb8 Nc6+ Qbxc6 Qgxf6+ Rxf6 Qxb8+ Qcc8 Qxf8+ Qde8 Qxd4+ Qd7 Bxf6# Qexd7+ Qcxd7 Ne6+ Kxe7 Nxd4+ Rxe5 Bxf6+ Qxf6 Qxf6+ Kxf6 Qh6+ Ke7 Qxd7+ Nfxd7 Rxe8+ Kxf7 Bxd5+ Rxd5 Re7+ Kxe7 Qg7+ Ke8 Qcc8+ Qd8 Qxd8# On K7/600 (350 MB hash) it took 11.7 hours to find both key moves, and 15.3 hours total time to also print a solution tree containing the above PVs. >Well, the effective branching factor is quite good for Chest. >Here is the timing for the increasing depths: > > seconds ># 1 0.00 0.87 1- 0 ># 2 0.00 1.00 1- 0 ># 3 0.00 0.95 70- 0 ># 4 0.08 1.07 465- 0 ># 5 0.37 1.27 2085- 0 ># 6 1.46 1.57 7901- 0 ># 7 6.32 2.09 34402- 0 ># 8 25.78 2.57 141569- 0 ># 9 87.41 3.28 500658- 0 ># 10 478.70 3.56 2712514- 478 ># 11 1570.93 4.26 8976242- 1058845 ># 12 7659.24 3.73 44489747- 35741846 # 13 41979.42 3.21 233216096- 224468195 >depth 7-> 8: 4.079 >depth 8-> 9: 3.390 >depth 9->10: 5.476 >depth 10->11: 3.281 >depth 11->12: 4.875 depth 12->13: 5.480 >It changes a bit up and down, but stays between 3 and 5.5 so far, which >is not bad for such a crowded board and 69 initial legal moves. > >But no cigar, yet. > >>>proven that lots of the other moves lose already though. >>>proved that 26 of the other moves lose after 10 minutes search.. >>> >>>Angrim > >Yes, for (nearly) all partial mate-in-3 Chest tried to mate the attacker >directly in 1 move, which succeeded in 16.2% of the cases. A more >sophisticated heuristic might succeed in many more cases. > >Now, Leonid, should I go on? Depth 13 and 14 will take around 9 hours >and 1.5 days! What is your shortest (selective) solution? > >Cheers, >Heiner My estimates above were even a bit low. This mate problem was definitely a heavy one. But I'm sure, you will not run out of such problems, Leonid :-) Happy weekend! Heiner
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