Author: Heiner Marxen
Date: 14:55:59 05/01/01
Go up one level in this thread
On May 01, 2001 at 12:34:19, Heiner Marxen wrote: >On May 01, 2001 at 07:55:26, leonid wrote: > >>On May 01, 2001 at 01:02:33, Paul Byrne wrote: >> >>>On April 29, 2001 at 07:32:15, leonid wrote: >>> >>>>Hello! >>>> >>>>I know that I should never indicate here any position like this, but it is just >>>>too seductive! Only really dedicated man or highly performant mate solver can >>>>crunch it. >>>> >>>>[D]Qrbqkbr1/Qn3qPP/NQqQq1nB/1qNqQBq1/1Qq1q2Q/8/3RR3/4K3 w - - >>>> >>>>Please indicate your result. >>>> >>>>Thanks, >>>>Leonid. >>> >>>That was a tough one! My PN search went through 512MB of memory without solving >>>it. PN2 got Qbxd8+ winning in 1316.46 seconds (100043829 nodes) -- the PN2 code >> >>Hi, Paul! >> >>What is PN2? > >I strongly suspect it is a modified version of "proof number search". >I seem to remember that Aske Plaat wrote about it. You should find >something with your favorite search engine (e.g. Google). > >>Your move is what mine found. >> >>Your solution was quick compared with mine. I actually had the impression that >>this position contain the mate and asked to search this position. Very deep >>selective search, 13 moves deep. Left my solver thinking in the night. Celeron >>600Mhz. No hash. It took almost 4 hours (3 h 56 min) to solve in 13 moves. But >>at what depth your found? Maybe your said that mate existe in 12 or even 11. >> >>Cheers, >>Leonid. > >Hi Leonid, > >According to Chest it is a mate in 13, i.e. no solution in 12 or less moves. >On a K7/600 with 350 MB hash Chest spends nearly 37 hours to find that >there are two key moves for the mate in 13: Qdxd8+ and Qbxd8+. >I have not yet a PV (the solution tree is not contained in the hash, any more, >and is currently recomputed). I will follow-up when it is there. Here are two PV lines from Chest: Qbxd8+ Qxd8 Qhxd8+ Nxd8 Qxd8+ Qxd8 gxf8Q+ Rxf8 Qxf7+ Rxf7 h8=Q+ Nf8 Qxf8+ Rxf8 Rxd8+ Ke7 Bg5+ Rf6 Bxf6+ Kf7 Rf8+ Kxf8 Nxe6+ Ke8 Qe7# Qdxd8+ Qgxd8 Qhxd8+ Nxd8 Qxd8+ Qxd8 gxf8Q+ Rxf8 Qxf7+ Rxf7 h8=Q+ Nf8 Qxf8+ Rxf8 Rxd8+ Ke7 Bg5+ Rf6 Bxf6+ Kf7 Rf8+ Kxf8 Nxe6+ Ke8 Qe7# They are basically equal. Other black moves lead to shorter solutions, except: 8... Kxd8 Nxe6+ Bxe6 Bg5+ Kc8 Qexb8+ Qxb8 Qaxb8+ Kd7 Qe7# Kd7 Nxb8+ Kc8 Nxc6+ Kd7 Qed6# Qb8 Qbb7# Qxb8 Qe7+ Kc8 Qexb8# Rxb8 Qe7+ Kc8 Qd8# Rf6 Qxf6+ Kd7 Qfe7+ Kc8 Qd8# Total computation time is 43.2 hours. Heiner >Here is the timing statistics: > >depth time[s] speed nodes in nodes out ># 1 0.00 0.94 1- 0 ># 2 0.01 1.00 1- 0 ># 3 0.03 0.97 88- 0 ># 4 0.20 1.12 612- 0 ># 5 1.06 1.31 3484- 0 ># 6 4.64 1.66 16340- 0 ># 7 17.77 3.27 67644- 0 ># 8 79.58 5.29 335490- 0 ># 9 385.99 7.30 1776286- 30 ># 10 1492.82 9.43 7245314- 342027 ># 11 5287.27 11.55 28318639- 19570743 ># 12 31346.51 10.79 174568973- 165821072 ># 13 132724.97 10.18 765545533- 756797632 > >Cheers, Heiner > > >>>is set up for suicide chess though and could probably be sped up a good bit for >>>regular chess. >>> >>>-paul
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