Author: Sune Larsson
Date: 15:48:52 03/24/01
Go up one level in this thread
On March 24, 2001 at 16:04:13, James T. Walker wrote: >On March 24, 2001 at 15:48:07, Derek Mauro wrote: > >>On March 24, 2001 at 15:46:06, Derek Mauro wrote: >> >>>On March 24, 2001 at 14:46:12, Derek Mauro wrote: >>> >>>>On March 23, 2001 at 17:50:15, James T. Walker wrote: >>>> >>>>>On March 23, 2001 at 14:35:06, Derek Mauro wrote: >>>>> >>>>>>On March 23, 2001 at 01:09:23, James T. Walker wrote: >>>>>> >>>>>>>On March 23, 2001 at 00:49:45, James T. Walker wrote: >>>>>>> >>>>>>>>On March 22, 2001 at 17:55:07, Derek Mauro wrote: >>>>>>>> >>>>>>>>>I'm no expert on computer chess, but I thought I'd call this to everyone's >>>>>>>>>attention. I was analyzing one of my recent games with Tiger (reg. and gambit), >>>>>>>>>and had a drawn position(I had black). >>>>>>>>> >>>>>>>>>[D]8/8/8/8/1n6/2K5/p7/6k1 w - - 0 111 >>>>>>>>> >>>>>>>>>For some reason, in the obvious draw, Tiger gives it -12 and wants to play >>>>>>>>>Kxb4?? even after like 20 minutes. All the programs seem to think its about -6 >>>>>>>>>or so, but they all play the correct move, the obvious Kb2. Is this a bug? >>>>>>>>>(The 4 piece tablebases will easily solve this bug, but this position is so >>>>>>>>>incredibly easy that I can't see why it would even need them.) >>>>>>>>> >>>>>>>>>This next position is also from the same game that all programs seem to have >>>>>>>>>trouble with, but I don't believe this is a bug. >>>>>>>>> >>>>>>>>>[D]8/1k6/2n5/8/6r1/p1K5/7R/8 b - - 0 87 >>>>>>>>> >>>>>>>>>Most programs want to play Nb4, but from there white can force a draw. I think >>>>>>>>>Ra4 is the correct move (Na5 might also work), but I'm not sure. I also fell to >>>>>>>>>the tempation of Nb4 during the game :( >>>>>>>>> >>>>>>>>>Derek >>>>>>>> >>>>>>>>Hello Derek, >>>>>>>>Can you post a line which gives white the draw after Nb4? It seems to me that >>>>>>>>black should still win this ending. What am I missing? >>>>>>>>Jim >>>>>>> >>>>>>>This is funny. The more I look at it the more I can't see how to win it either! >>>>>>>:-) >>>>>>>Jim >>>>>> >>>>>>The rest of the game went like this: >>>>>>87... Nb4 88. Rh7+ Ka6 89. Kb3 a2 90. Rh6+ Kb5 91. Rh5+ Kb6 92. Rh6+ Kc5 93. >>>>>>Rh5+ Kd4 94. Rh1 Kd3 95. Rd1+ Ke2 96. Rh1 Kd2 97. Rh2+ Ke3 98. Rh3+ Kf2 99. Rh1 >>>>>>Rf4 100. Ra1 Ke2 101. Kc3 Re4 102. Rh1 Ke3 103. Re1+ Kf2 104. Ra1 Rg4 105. Kb3 >>>>>>Ke3 106. Kc3 Ke2 107. Rh1 Ke3 108. Re1+ Kf2 109. Ra1 1/2-1/2 >>>>>> >>>>>>Trading rooks on the 1st rank results in the position in the first diagram. All >>>>>>those moves are pretty much forced. There are a couple other moves in there, >>>>>>but none of them work (I think). There is no way to trade rooks closer to the >>>>>>promotion square, I already tried that. I think Ra4 was better, because it >>>>>>allows the knight to move and eventually attack the promotion square. >>>>>>Supporting a pawn from behind with a rook is also a basic principle. Very tough >>>>>>endgame! >>>>> >>>>>I worked on this a little while today with Fritz 6e.. This is what "we" came up >>>>>with. 1....Nb4 2. Rh7+ Kc6 3. Kb3 a2 4. Rh6+ Kd5 5. Rh1 Rh4 6. Rg1 Kc5 7. Rg5+ >>>>>Kd4 8. Rg1 Rh8 9. Kb2 Ra8 10. Rd1+ Ke3 11. Ra1 Nd3 12. Kb3 Kd4 13. Kc2 Rb8 14 >>>>>Kd2 Rb2+ & mate in 9 ..... 0-1 >>>>> >>>>>I think if Sune Larrson can post lines like this, then so can I. :-) >>>>>I have no idea if this would really work or not so just consider it as a >>>>>"dream". >>>>>Jim >>>> >>>>I think that 5. Rh1 is an inaccuracy. The black king want to be on c5. I think >>>>5. Ra4+ is better because then if the king moves to the 4th rank, that whole >>>>trick with Rh4 is impossible, since the king has to be on c5. Computers don't >>>>help too much here. >>> >>>Sorry, I meant 5. Ra5+ instead of 5.Ra4+. >> >>I am losing my mind. 5.Rh5+ I meant (I hope I got it right this time :) > >I don't see what 5. Rh5+ accomplishes. It just drives the black King to d4 >which is where it wants to go anyway. In my variation it made it at move 7. >The white rook eventually has to guard a1 by putting the rook on the first rank >anyway. After 5. Rh5 Kd4 then Ra5? leads to mate in 8 so where is the white >rook going? >Jim Yes, transforming the black rook to a8 is a very strong and beautiful idea! In the original game above, it looks like black missed his chances at several occasions: 94.-Rg8!, 99.-Rg8!, 102.-Re8! all carrying the same idea. Here is one of the positions that could follow: [D]r7/8/8/8/1n6/1K3k2/p7/R7 b - - 0 19 Black is on the move and has the nice resource 1.-Ke3! (there is also 1.-Nd3) The "Hauptvariante" is beautiful! 2.Kxb4 Kd3! (this position could also happen if white takes the knight before the rooks are played to the a-file.) 3.Kb3 Rb8+! 4.Ka3 (if 4.Kxa2 Kc2) 4.-Kc2! 5.Rxa2+ Kc3! and black wins. Sune
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