Author: Frederic Friedel
Date: 12:45:37 01/15/00
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On January 15, 2000 at 12:07:26, Mike S. wrote: >Hi Henk, >this could be a "null move" problem. [snip] >P.S. >What is the source of this position? I think I've seen it before. First the source. It is a study by M. Klyatskin, and appeared in Schachmat 1924. [D]rR6/p7/KnPk4/P7/8/8/8/8 w - - 0 1 The full solution: 1.c7! [1.Rxa8? Nxa8 A) 2.Kb7 Nc7 3.a6 (3.Kxa7 Kxc6=) 3...Nxa6=; B) 2.Kxa7 2...Kxc6 3.Kxa8 Kb5=; 1.axb6 Rxb8 2.bxa7 (2.Kxa7 Kxc6) 2...Re8 3.Kb7 Re7+ (3...Ra8 4.Kxa8 Kc7) ] 1...Kxc7 2.axb6+!! Kxb8 3.b7+- 1-0. [PGN given below]. You are right, Michael, it is a null move problem. I can give you dozens of Zugzwang positions which Fritz cannot solve in its default settings. However, if you go to the "Engine parameters" and change the "Selectivity" from its default value of 2 to 0 (effectively switching off null move) then Fritz 5.32 and 6 will solve the problem, i.e. play 2.axb6+!! immediately. When testing this I noticed something odd. My Fritz 6.0 solves it instantaneously even if selectivity is set to 2. This I don't quite understand, and will have to check further. I only spent a few minutes on this so far. Maybe the answer is that I've installed the new version 6a (yes, yes, which will be generally available in the coming week). I deleted my original Fritz6 engine so I cannot easily check what that would have done. In the process I also "discovered" a neat feature (yes, yes, it's not described in the manual). Right-click the analysis and select "Clip analysis". Then press Ctrl-V to paste it in your message. You get the following: Klyatskin,M - [+0403.21a6d6 rR6/p1k5/Kn6/P7/8/8/8/8 w - - 0 1 Analysis by Fritz 6: 2.Rxa8 -+ (-2.16) depth: 1/3 00:00:00 2.Rxa8 Nxa8 3.Kxa7 ± (0.72) depth: 1/4 00:00:00 2.Rxa8 Nxa8 3.Kxa7 ± (0.72) depth: 2/5 00:00:00 2.Rxa8 Nxa8 3.Kxa7 Kd6 ± (0.72) depth: 3/6 00:00:00 2.axb6+ ± (0.94) depth: 3/9 00:00:00 2.axb6+ axb6+ 3.Rxa8 Kc6 +- (3.94) depth: 3/9 00:00:00 2.axb6+ axb6+ 3.Rxa8 Kc6 4.Rc8+ Kd7 +- (3.94) depth: 4/8 00:00:00 2.axb6+! +- (5.47) depth: 5/7 00:00:00, tb=4 2.axb6+! Kd6 3.bxa7 Kd7 4.Rxa8 Kc7 +- (7.09) depth: 5/11 00:00:00 1kN, tb=8 2.axb6+! +- (7.63) depth: 6/7 00:00:00 1kN, tb=12 2.axb6+! Kxb8 3.b7 Kc7 4.bxa8Q Kd6 5.Qxa7 +- (9.03) depth: 6/9 00:00:00 1kN, tb=14 2.axb6+ Kxb8 3.b7 Kc7 4.bxa8Q Kd6 5.Qxa7 +- (9.03) depth: 7/9 00:00:00 2kN, tb=19 2.axb6+! +- (#18) depth: 8/9 00:00:00 3kN, tb=25 (Friedel, Hamburg 15.01.2000) Here's the position and solution in PGN, so you can play around with it. [Event "2/83-16 Schachmat"] [Site "?"] [Date "1924.??.??"] [Round "?"] [White "Klyatskin, M.G.."] [Black "[+0403.21a6d6]"] [Result "1-0"] [SetUp "1"] [FEN "rR6/p7/KnPk4/P7/8/8/8/8 w - - 0 1"] [PlyCount "5"] [EventDate "1924.??.??"] 1. c7 $1 (1. Rxa8 $2 Nxa8 2. Kxa7 (2. Kb7 Nc7 3. a6 (3. Kxa7 Kxc6 $10) 3... Nxa6 $10) 2... Kxc6 3. Kxa8 Kb5 $10) (1. axb6 Rxb8 2. bxa7 (2. Kxa7 Kxc6) 2... Re8 3. Kb7 Re7+ (3... Ra8 4. Kxa8 Kc7)) 1... Kxc7 2. axb6+ $3 Kxb8 3. b7 $18 1-0
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