Author: Heiner Marxen
Date: 15:31:55 01/21/01
Go up one level in this thread
On January 21, 2001 at 16:08:25, Uri Blass wrote: >On January 21, 2001 at 15:22:30, Heiner Marxen wrote: > >>On January 21, 2001 at 14:13:30, leonid wrote: >> >>>On January 21, 2001 at 13:44:00, Heiner Marxen wrote: >>> >>>>On January 21, 2001 at 13:16:22, leonid wrote: >>>> >>>>>On January 21, 2001 at 12:43:34, Heiner Marxen wrote: >>>>> >>>>>>On January 21, 2001 at 11:56:09, leonid wrote: >>>>>> >>>>>>>Hi! >>>>>>> >>>>>>>This mate position is very handy when you want to check the limits in your >>>>>>>program. It is amusing also. Number of legal moves for both sides is slightly >>>>>>>over one hundred. >>>>>>> >>>>>>> knq3q1/rq1q1qbQ/Qq2Q3/1Qn1Q2B/Q1qN1Q1r/4K1B1/1q4QR/1N1q3Q white to go. >>>>>> >>>>>>A hint to you, Leonid: if you like to see a diagram for the notation above: >>>>>>(1) Stick a [D] directly before the FEN string, >>>>>>(2) append (blank seperated) colour to move, i.e. b or w >>>>>>(3) append (blank seperated) castling rights: - for nothing, KQkq or part >>>>>> of it for white/black king side/queen side >>>>>>(4) append (blank seperated) e.p. info: - for "no e.p. possible" >>>>>>You can look up the details in the FEN standard, part of the PGN standard. >>>>>>Look at the line below, which I typed in, and see the diagram, provided not >>>>>>by me, but by the CCC web server, which recognizes the [D] and FEN after it, >>>>>>and inserts the graphics. You can do that also. >>>>> >>>>>Thanks! Will try to use it the next time. >>>>> >>>>>Leonid. >>>>> >>>>> >>>>>>[D]knq3q1/rq1q1qbQ/Qq2Q3/1Qn1Q2B/Q1qN1Q1r/4K1B1/1q4QR/1N1q3Q w - - >>>>>> >>>>>>Chest says "no mate in 9" (216 seconds, K7/600 335MB hash). >>>>>>I will ask for more depth... >>>>> >>>>>Are there no mistake? You have really 335Mb hash? >>>> >>>>Yes! :-) >>>>I bought 512 MB. Was a bit expensive, but my monitor costs even more. >>>>And on work I have seen what 512MB can do to big Chest jobs, so I really >>>>wanted to have so much memory. I like it :-) >>> >>>And what the monitor you have? 21 inch? >>> >>>The last time, around 3 months ago, I bought my last 17 inch. Very cheap and >>>very good. My next dream is new computer. I need it for my programming. >> >>It is a 15.1 inch TFT screen. It had to fit into this tiny room, where >>my computer is placed. I am very satisfied with it, but it is not cheap. >> >>>>>216 sec for 9 moves like very good. I went, by brute force, only up to 7 moves. >>>>>It was already 2 min. 19 sec. But for this position, which look very heavy, >>>>>branching factor was very normal. Like what you can expect from usual forced >>>>>mate position. >>>>> >>>>>4 moves - 0.77 sec >>>>> branching factor 5.8 >>>>>5 moves - 4.39 sec >>>>> 5.3 >>>>>6 moves - 23.02 sec >>>>> 6.1 >>>>>7 moves - 2 min 19 sec >>>> >>>>Yes, black has also 9 queens, and whites king is exposed. If white does >>>>anything not really forcing, black will start to force, or even mate. >>>>Therefore the search trees can be small in many branches. In 17% of all >>>>considered cases, black mates white! (yes, Chest tries that sometimes) >>>> >>>>Here are my numbers: >>>> >>>># 1 0.00 0.87 1- 0 >>>># 2 0.01 1.00 1- 0 >>>># 3 0.03 0.96 107- 0 >>>># 4 0.19 1.04 819- 0 >>>># 5 0.87 1.23 4167- 0 >>>># 6 3.73 1.48 17787- 0 >>>># 7 14.90 1.79 72503- 0 >>>># 8 56.43 2.17 290160- 0 >>>># 9 213.00 2.57 1142162- 0 >>>># 10 831.85 2.90 4544295- 16385 >>>>(depth seconds speed node in node out >>> >>>Pretty good branching factor! >> >>Yes, and here is the next line: >># 11 3686.85 2.90 20110217- 11363105 >> >>Chest does not find any mate in 11. >> >>>>>Leonid. >>>>> >>>>>>Heiner >>>>>> >>>>>>>If you will solve, it will be nice if you will indicate your result. >>>> >>>> >>>>Is there any forced solution, at all? Depth=11 will take around an hour, >>>>and I will not go much further, if there is no real chance. >>> >>>For 11 moves I don't know. My solved it by selective only at 12. Actually, this >>>position is more that strange. Solution was found by the most easy level in >>>selective search. Because of very good for me branching factor, I expected it >>>will be instant. It was not so. It took 2 seconds. >>> >>>Leonid. >> >>Fine, so I stop this, now. Looks like there is no shorter mate, >>which is not surprising for a position like this one. >> >>I just asked crafty 17.7 for a depth=1 analysis, and even after 3 minutes >>I still see no output ;-) Obviously the quiescence search is exploding. >> >>Can you give some PV for the forced #12 line? Just curious. >> >>Heiner > >1.Qxa7+ Qxa7 2.Qxa7+ Kxa7 3.Qgxb7+ Qdxb7(to prevent the threat Qxb8+) >4.Qexc5+ Q4xc5(Ka8 Qxb8+ and Qb7 is pinned) 5.Qxb8+ Qcxb8(Qbxb8 Bxb8+ mate in 2) >6.Qxc5+ Q7b6(Q2b6 let Ra2+) and I guess that now chest has no problem to see >that 7.Bxb8+ is a mate in 6. > >Uri I let Chest analyse after 1.Qxa7+ Qxa7 2.Qxa7+ Kxa7, and can confirm your line upto but excluding 6.Qxc5+, where Chest choose to do 6.Bxb8+. I suspect both moves are ok. BTW, after the first two moves besides 3.Qgxb7+ also 3.Qexc5+ and 3.Qeb6+ solve this. I like the last one (it does not even capture): 3.Qeb6+ Ka8 4.Qgxb7+ Qdxb7 5.Qxb8+ Qxb8 6.Qxb8+ Qxb8 7.Q6a5+ Na6 8.Qaxa6+ Qa7 9.Qg8+ Bf8 10.Qxf8+ Qe8+ 11.Qbxe8+ Qc8 12.Qxc8# Crafty 17.7 after over 2 hours still has not completed depth=1 ;-) I think Bob will not care much, since this position is not at all for real. Heiner
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