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Subject: Re: BS 2830 Problem #5 is wrong.

Author: Vasik Rajlich

Date: 14:12:19 03/17/04

Go up one level in this thread


On March 17, 2004 at 13:07:09, Anthony Cozzie wrote:

>On March 17, 2004 at 12:44:23, Vasik Rajlich wrote:
>
>>On March 17, 2004 at 10:41:00, Vincent Diepeveen wrote:
>>
>>>On March 17, 2004 at 09:58:37, martin fierz wrote:
>>>
>>>>On March 17, 2004 at 08:57:28, Vasik Rajlich wrote:
>>>>
>>>>>On March 17, 2004 at 08:19:21, Joachim Rang wrote:
>>>>>
>>>>>>On March 16, 2004 at 18:58:46, Dann Corbit wrote:
>>>>>>
>>>>>>>See this thread:
>>>>>>>http://www.talkchess.com/forums/1/message.html?354948
>>>>>>
>>>>>>well after some study with Shredder 8 it is my opinion, that the testposition is
>>>>>>wrong in that aspect, that it is not clear whether Rxe6 is the only move to win
>>>>>>the game. But I am quite sure, that it is a winning move, but Qh3 dould be
>>>>>>winning also (most likely I think).
>>>>>>
>>>>>>The main variation after Rxe6 is the following one:
>>>>>>
>>>>>>1.Rxe6 Qxe6 2. Rde1 Qf5 (Qd6 3.Bf4 h5 4. Qxc8 Rxc8 5. Bxd6 Bxd6 6. Bxd5+ +-) 3.
>>>>>>Qxf5 gxf5 (all other moves loose instantly) 4. Bxd5+ Kg6 (only move):
>>>>>>
>>>>>>Now Shredder 8 gives + 2.36 at depth 25. This is not a prove but it seems
>>>>>>unlikely that this position is not won for white.
>>>>>>
>>>>>>As i posted before I get +1.98 wiht a 24ply-search for 1. Qh3 in the
>>>>>>startposition, which also seems rather convincing, that this move will lead to a
>>>>>>win too. But I was too lazy to create variations here).
>>>>>>
>>>>>>regards Joachim
>>>>>>
>>>>>
>>>>>Shredder is very optistic in evaluating endgames.
>>>>>
>>>>>Here, for example, take the PV in the 25-ply analysis, which starts with
>>>>>5.Bh6-d2 Kg6-g7 6.Bd2-f4 b6-b5 7.g2-g3 b5-b4 8.Kg1-g2.
>>>>>
>>>>>The PV continues with 8. .. a5, but instead black can just play 8. .. bxa3 9.
>>>>>bxa3 Na5. Now let's play vs Shredder for a few moves: 10. Be6 Bxa3 11. Bxc8 Rxc8
>>>>>12. Ra1 Bb4 13. Bd2 Bxd2 14. Nxd2 Rc2 15. Nf3 Nc4 16. Rxa7+ Kf8 17. Nh4 Ne3+ 18.
>>>>>Kf3 Nd1 19. Kf4 Rxf2+ 20. Nf3 Nc3 21. Rxh7 Ne4 22. h4 Nd2 (finally scores go
>>>>>under +2.0) 23. Ke3 Rxf3+ 24. Kxd2 Rxg3 and black is drawing.
>>>>
>>>>another thing to keep in mind is that shredder's PV is unreliable. you can't
>>>
>>>this is a very good remark.
>>>
>>>Also note that the +1.9 for qh3 is basically because of the bad black king and
>>>white having more space.
>>>
>>>If you close your eyes, what position do you prefer to play Rxe6 or Qh3?
>>>
>>>I cannot understand that there is so many beginners here who prefer to play the
>>>very complex qh3 because 1 program which prunes even itself and its mainline
>>>says +1.9.
>>>
>>>After Rxe6 it is very clear. White is dead won and the only question is whether
>>>you win it eyes closed or whether you can also win it when asleep.
>>>
>>>That a computer doesn't score Rxe6 like +4.0 nor +5.0 is because white is down
>>>the exchange and a piece in shredder is already like 4.5 pawns or so, not to
>>>mention a rook. So pawns simply do not compensate for being an exchange down.
>>>
>>>So the 2.5 score shredder shows for Rxe6 you should see as +10.0 or so from
>>>human viewpoint. White can do nothing wrong and still will win.
>>>
>>>If i take some 1800 rated kids from my chessclub i'm sure that after Rxe6 gets
>>>played, that they will win from me with white. If they have white and play Qh3 i
>>>still win from them.
>>>
>>>Rxe6 leads to either mate, some big material win, or a dead won endgame.
>>>
>>>Even deep study i didn't find anything to delay a quick loss from black.
>>>
>>>However the number of moves and nullmoves you can do in the process is really a
>>>lot. 25 ply of shredder is like 3 nullmoves and 3 moves collecting material for
>>>white. What's beyond those nullmoves?
>>>
>>>I prefer to play a 25 ply searching shredder above a 15 ply searching shredder.
>>>
>>>It can only make mistakes with such dubious forward pruning or see more problems
>>>for it :)
>>>
>>
>>Sheesh, tough crowd :-) Ok, this time I played the position against Shredder 7
>>(don't have my normal setup here), 1 min/move for Shredder, Athlon XP 2600+.
>>Result: draw. Didn't even need to take any moves back.
>>
>>Shredder 7 - V. Rajlich, Warszawa 17.3.04 (BTS2830 #5 after 1. Rxe6 Qxe6 2. Re1
>>Qf5 3 Qxf5 gxf5 4. Bxd5+ Kg6)
>>
>>5. Bf4 Nxd4 6. Nxd4 Bxa3 7. Rxe8 Rxe8 8. g4 Bxb2 9. Nxf5 Bc1 10. Bd6 a5 11. Kf1
>>h5 12. f3 hxg4 13. fxg4 Kg5 14. Bf3 Rh8 15. h4 Rxh4+ 16. Nxh4 Kxh4 17. Ke2 Kg5
>>18. Kd3 f5 and adjudicated 1/2-1/2
>>
>>Vincent you can laugh at Shredder's play, but does Diep have the knowledge to
>>win this endgame?
>>
>>Cheers,
>>Vas
>
>What is your background? IM, but with BS in CS? 2350 FIDE? I'm sort of curious.
>
>anthony
>

Hi Anthony,

All right, I'll fix up my profile a little bit.

Actually, it wouldn't be a bad idea if the board collected some other info,
pics, maybe CVs. I'm curious too about some people who post here - plus, we'd
know what Swami looks like.

BTW, I see you're from DC. Not by any chance a 'Skins fan?

Vas

>>>>just move down several moves of the PV and then let it search again, you have to
>>>>let it think at every move :-(
>>>>
>>>>my impression about the position after 1.Rxe6 Qxe6 2. Rde1 Qf5 3.
>>>>Qxf5 gxf5 4. Bxd5+ Kg6 is that it is not a clear win - there is definitely some
>>>>work ahead here. perhaps stronger players see this differently, but i think
>>>>black has some hope left....
>>>>
>>>>cheers
>>>>  martin
>>>>
>>>>
>>>>
>>>>>I think SMK's point in scoring endgames in this way is that it's very pleasant
>>>>>in a tournament to play a position like this, there are no risks. If you win two
>>>>>pawns in some unclear middlegame, there might be something you didn't evaluate
>>>>>or calculate. In this sort of position, only good things can happen. That's why
>>>>>Shredder gives +2, not because it's flat-out winning.
>>>>>
>>>>>Cheers,
>>>>>Vas
>>>>>
>>>>>>P.S.:
>>>>>>New game
>>>>>>2r1r3/p3b2p/1pn2pkB/3B1p2/3P4/P4N2/1P3PPP/4R1K1 w - - 0 1
>>>>>>
>>>>>>Analysis by Shredder 8:
>>>>>>
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.Bd5-e6 Rc8-d8 8.d4-d5 Be7-d6 9.Bf4xd6 Re8xe6
>>>>>>10.Re1xe6
>>>>>>  +-  (1.58)   Depth: 13/13   00:00:00  27kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 h7-h5 7.g2-g3 b6-b5 8.Bd5-e6 Rc8-d8 9.d4-d5 Nc6-e5
>>>>>>10.Nf3xe5 f6xe5 11.Re1xe5 Be7-d6 12.Re5xf5 Bd6xf4 13.Rf5xf4
>>>>>>  +-  (1.62)   Depth: 14/24   00:00:02  738kN
>>>>>>5.Bh6-f4 Kg6-g7 6.b2-b4 b6-b5 7.Re1-c1 Nc6-b8 8.Rc1xc8 Re8xc8 9.Nf3-h4 Kg7-f8
>>>>>>10.Bd5-b7 Rc8-c3 11.Nh4xf5 Nb8-c6 12.a3-a4 Nc6xb4 13.a4xb5
>>>>>>  ±  (1.38)   Depth: 15/26   00:00:07  2369kN
>>>>>>5.Bh6-f4 Nc6xd4 6.Nf3xd4 Be7xa3 7.Re1xe8 Rc8xe8 8.Nd4-f3 Ba3xb2 9.Nf3-h4+ Kg6-g7
>>>>>>10.Kg1-f1 a7-a5 11.Nh4xf5+ Kg7-f8 12.Nf5-d6 Kf8-e7
>>>>>>  ±  (1.33)   Depth: 16/30   00:00:23  7471kN
>>>>>>5.Bh6-f4 Nc6xd4 6.Nf3xd4 Be7xa3 7.Re1xe8 Rc8xe8 8.g2-g4 Ba3xb2 9.g4xf5+ Kg6-g7
>>>>>>10.Nd4-e6+ Kg7-h8 11.Kg1-f1 Re8-c8 12.Kf1-e2 Rc8-c2+ 13.Ke2-e3 a7-a5
>>>>>>  ±  (1.31)   Depth: 17/32   00:00:43  15168kN
>>>>>>5.Bh6-d2 Kg6-g7 6.Bd2-f4 h7-h5 7.b2-b4 b6-b5 8.Bd5-e6 Rc8-d8 9.d4-d5 Nc6-b8
>>>>>>  ±  (1.32)   Depth: 17/43   00:00:53  19035kN
>>>>>>5.Bh6-d2 Kg6-g7 6.Bd2-f4 b6-b5 7.Bd5-e6 Rc8-d8 8.d4-d5 Nc6-e5 9.Nf3-d4 Ne5-d3
>>>>>>10.Be6xf5 Nd3xe1 11.Nd4-e6+ Kg7-f7 12.Ne6-g5+ f6xg5 13.h2-h4 g5xf4
>>>>>>  ±  (1.32)   Depth: 17/43   00:01:03  22267kN
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 b6-b5 7.Bd5-e6 Rc8-d8 8.d4-d5 Nc6-e5 9.Nf3-d4 Ne5-c4
>>>>>>10.Bd2-c1 Nc4-e5 11.Nd4xb5 Ne5-d3 12.Re1-f1 Nd3xc1
>>>>>>  +-  (1.43)   Depth: 18/36   00:02:07  44465kN
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 h7-h5 7.Bd2-f4 b6-b5 8.Re1-c1 Nc6-b8 9.Rc1xc8 Re8xc8
>>>>>>10.Nf3-h4 Kg7-f8 11.Nh4xf5 Be7xb4 12.a3xb4
>>>>>>  +-  (1.63)   Depth: 19/36   00:03:26  71268kN
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 h7-h5 7.Re1-c1 Nc6-b8 8.Rc1xc8 Re8xc8 9.Nf3-h4 Be7-f8
>>>>>>10.Nh4xf5+ Kg7-g6 11.Bd5-e4 Rc8-d8 12.Bd2-f4 Kg6-f7 13.d4-d5 Rd8-e8 14.f2-f3
>>>>>>a7-a5 15.b4xa5
>>>>>>  +-  (1.69)   Depth: 20/38   00:06:04  127926kN
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 a7-a5 7.Re1-e6 Nc6-d8 8.Re6xb6 a5xb4 9.a3xb4 Rc8-c2
>>>>>>10.h2-h4 Rc2-b2 11.g2-g3 Nd8-f7 12.Bd5-c6 Re8-c8 13.Kg1-h2
>>>>>>  +-  (1.69)   Depth: 21/40   00:10:18  218263kN
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 a7-a5 7.Re1-e6 Nc6-d8 8.Re6xb6 a5xb4 9.a3xb4 Rc8-c2
>>>>>>10.h2-h4 Rc2-b2 11.g2-g3 h7-h5 12.b4-b5 Be7-b4 13.Bd2-e3 Nd8-c6
>>>>>>  +-  (1.84)   Depth: 22/41   00:17:10  366131kN, tb=1
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 a7-a5 7.Re1-e6 Nc6-d8 8.Re6xb6 a5xb4 9.a3xb4 Rc8-c2
>>>>>>10.h2-h4 Rc2-b2 11.g2-g3 h7-h5 12.b4-b5 Be7-b4 13.Bd2-e3 f5-f4 14.Be3xf4
>>>>>>  +-  (1.79)   Depth: 23/44   00:29:23  635510kN, tb=1
>>>>>>5.Bh6-d2 Kg6-g7 6.b2-b4 a7-a5 7.Re1-e6 Nc6-d8 8.Re6xb6 a5xb4 9.a3xb4 Rc8-c2
>>>>>>10.g2-g3 Nd8-f7 11.Kg1-g2 Nf7-d6 12.Bd5-c6 Re8-c8 13.b4-b5
>>>>>>  +-  (1.76)   Depth: 24/46   00:55:18  1220985kN, tb=1
>>>>>>5.Bh6-d2 Kg6-g7 6.Bd2-f4 b6-b5 7.g2-g3 a7-a6 8.Kg1-g2 Nc6-a5 9.Bd5-e6 Rc8-c6
>>>>>>10.Be6-d7 Re8-d8 11.Re1xe7+ Kg7-f8 12.Bd7xc6 Kf8xe7 13.d4-d5
>>>>>>  +-  (2.01)   Depth: 25/44   02:02:56  2697532kN, tb=4
>>>>>>5.Bh6-d2 Kg6-g7 6.Bd2-f4 b6-b5 7.g2-g3 b5-b4 8.Kg1-g2 a7-a5 9.Bd5xc6 Rc8xc6
>>>>>>10.d4-d5 Rc6-c8 11.d5-d6 b4xa3 12.d6-d7 Be7-f8 13.Re1xe8
>>>>>>  +-  (2.36)   Depth: 25/47   02:26:20  3183940kN, tb=4



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