Author: John Merlino
Date: 13:31:32 08/28/01
Go up one level in this thread
On August 26, 2001 at 14:56:24, Eduard Nemeth wrote: >On August 26, 2001 at 14:40:33, Roy Eassa wrote: > >>[D] 8/2r1k2p/p3p1p1/3r1p2/8/1P3PP1/P2RK2P/3R4 b - - >> >>I reached this position as white recently, and after the game I used Gambit >>Tiger 2.0 to help analyze. What occurred in the game was: >> >>1... Rcd7(?) 2. Rxd5 Rxd5?? 3. Rxd5 exd5 >> >>after which I believe white should win (which I did). I believe it's very bad >>for black to trade off both pairs of rooks, and best to avoid allowing white to >>exchange even one pair of rooks here because of isolating black's pawn. >> >>It appears that Gambit Tiger 2 on my Athlon 1.2 GHz does not really understand >>that after move white's move 3 above, white should win. And it believes the >>position is essentially equal after white's move 2. >> >>Here is its analysis after black's move 1: >> >>00:00:00.9 0.22 9 168541 h3 Kf6 Rxd5 exd5 Rc1 Ke6 Kd3 f4 Rc6+ Rd6 Rxd6+ Kxd6 >>00:00:00.3 0.16 9 184134 h3 Rxd2+ Rxd2 Rxd2+ Kxd2 e5 Ke3 Ke6 g4 fxg4 fxg4 h5 a3 >>hxg4 hxg4 >>00:00:01.9 0.12 10 445643 h3 Rxd2+ Rxd2 Rc7 Kd1 e5 Rc2 Rxc2 Kxc2 e4 fxe4 fxe4 >>Kc3 >>00:00:01.4 0.16 10 710893 Rxd5 Rxd5 Rc1 Kd6 Rc8 Rc5 Rxc5 Kxc5 Kd3 Kb4 h4 Ka3 >>00:00:02.8 0.16 11 905910 Rxd5 Rxd5 Rc1 Kd6 Rc8 Rc5 Rxc5 Kxc5 Kd3 Kd5 g4 e5 gxf5 >>gxf5 >>00:00:03.0 0.16 12 1519152 Rxd5 Rxd5 Rxd5 exd5 b4 Ke6 Ke3 Ke5 f4+ >>00:00:05.5 0.16 13 2286175 Rxd5 Rxd5 Rxd5 exd5 b4 Ke6 Ke3 Ke5 f4+ Kd6 a4 Ke6 Kd4 >>h6 b5 axb5 axb5 >>00:00:09.6 0.18 14 3833264 Rxd5 Rxd5 Rxd5 exd5 b4 Ke6 Ke3 h6 f4 g5 a3 gxf4+ Kxf4 >>d4 Kf3 d3 Ke3 >>00:00:18.1 0.20 15 7566502 Rxd5 Rxd5 Rxd5 exd5 b4 Kd6 Ke3 g5 f4 gxf4+ Kxf4 d4 a3 >>h5 Kf3 d3 Ke3 >> >> >>but after 2. Rxd5, suddenly Tiger prefers black to recapture with the pawn >>rather than the rook, and its evaluation becomes worse for black. >> >>Non-Gambit Tiger behaves very similarly. >> >>Is the lack of endgame knowledge in me or the program, or is it something else? >> >>(Using 96MB hash; Not using table bases.) > >This is NOT (!!) only position who Tiger have on "blackout" to pawn endgame. >This is real! > >here an other position (from a game Eduard - Tiger): > >[D]3k3r/1r4pp/p3Rp2/8/p7/2P5/P4PPP/R5K1 b - - 0 27 > >Tiger played now Re8??? and after Rd1+ game was lost for Tiger! > >(German: es gibt noch viel zu tun Christophe - vor allem im Bauernendspiel= >pawn endgame!) > >Eduard It appears to me that this game is lost for Black anyway. It takes almost 30 plies (from immediately after 1...Re8) to see that 1...Re8 loses to: 2.Rd1+ Rd7 3.Rxd7 Kxd7 4.Rxe8 Kxe8 5.Kf1 Kd7 6.Ke2 Kd6 7.Kd3 Kd5 8.c4+.... and the eval here (in a 1 minute search after 8.c4+) is almost the same as it is in the initial position (a little over +1 for White). So, I'm not sure that 1...Re8 is THAT much worse than 1...Ra7. In a bullet game, Chessmaster 8000 would play either 1...Ra7 or 1...Re8. On my PIII-600, it sticks with Re8 for a little over a minute, before switching back to Ra7 (which is ALSO still lost, is it not?): Time Depth Score Positions Moves 0:00 2/5 1.06 25450 27...Ra7 28. Rb1 Kc8 29. Rd1 Rd8 0:00 2/6 1.05 55817 27...Ra7 28. Rb1 Kd7 29. Re4 a3 30. Rd1+ Kc6 31. Red4 0:02 3/7 1.05 141003 27...Ra7 28. Rb1 Kd7 29. Rbe1 Rc7 30. Rxa6 Rhc8 0:05 4/8 1.10 406900 27...Ra7 28. Rb1 Kd7 29. Rbe1 Kc8 30. Rc6+ Kb8 31. Rb6+ Kc8 32. Rb4 a3 33. Re6 0:06 4/8 1.06 513566 27...Re8 28. Rxa6 Re4 29. Ra8+ Ke7 30. Rh8 h6 31. Rd1 Rc7 0:11 5/9 1.05 982887 27...Re8 28. Rxa6 Re4 29. Ra8+ Ke7 30. f3 Rc4 31. Re1+ Kd6 32. Ra6+ Kc5 33. Ra5+ Rb5 34. Ra7 0:26 6/10 1.01 2460505 27...Re8 28. Rxa6 Re4 29. Ra8+ Ke7 30. Rd1 Rc7 31. f3 Rec4 32. Ra6 Rd7 1:11 6/10 0.98 6335025 27...Ra7 28. Kf1 Kc8 29. Rc6+ Kd7 30. Rc4 a3 31. Rd1+ Ke7 32. Rc6 Rd8 33. Re1+ Kf8 3:39 7/11 0.98 19430802 27...Ra7 28. Rb1 Kd7 29. Re4 a3 30. Ra4 Rc8 31. Rxa3 Rc6 32. Re1 Kd6 33. Re3 jm
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