Author: blass uri
Date: 01:23:17 06/10/00
Go up one level in this thread
On June 10, 2000 at 01:01:54, blass uri wrote:
>On June 09, 2000 at 18:11:37, Ed Schröder wrote:
>
>>On June 09, 2000 at 05:39:21, blass uri wrote:
>>
>>>On June 09, 2000 at 01:11:03, Paulo Soares wrote:
>>>
>>>>On June 09, 2000 at 00:08:07, Oliver Roese wrote:
>>>>
>>>>>On June 09, 2000 at 00:03:02, Paulo Soares wrote:
>>>>>
>>>>>>On June 08, 2000 at 22:49:28, Oliver Roese wrote:
>>>>>>
>>>>>>> [Event "NRW 4er-Pokal"]
>>>>>>> [Site "Germany"]
>>>>>>> [Date "2000.06.04"]
>>>>>>> [Round "?"]
>>>>>>> [White "Grimm, S."]
>>>>>>> [Black "N.N"]
>>>>>>> [Result "1/2-1/2"]
>>>>>>> [FEN "8/4k1pp/5p2/P1p1p3/2Qq4/1P4P1/5PKP/8 b - - 0 1"]
>>>>>>>
>>>>>>> 1...Qxc4 ({This position occured last sunday in a team event. It was the
>>>>>>>last game. I and a team colleague of mine were "kibitzes". Our man had white.
>>>>>>>Obviously black is in trouble here. But black has the chance here to swap the
>>>>>>>queens and go into a pawn ending. He pondered a while and finally he played
>>>>>>>1...Qd6. The game went on with 2.Qe4 and finally he lost. My teammate took me
>>>>>>>aside: "What do you think about 1.Qxc4?" he asked. "Well, white opens the
>>>>>>>kingside with g4 and wins.", i said. "Wrong!" he told me. We made a blindgame,
>>>>>>>me playing white and he took me along up to the 18th move in this analysis. "I
>>>>>>>see.", i said, "But maybe white has some other possibilities." I went to the
>>>>>>>board, puzzled a while, and came back. "What about f4?" i asked. He hesitated
>>>>>>>shortly and showed me the winning line for black. In a few seconds he refuted a
>>>>>>>line that costed me several minutes! I went to the board again, trying hard to
>>>>>>>refute Qxc4. Eventually i came back. "What about g4, Kg3 and then f4?" He
>>>>>>>ponderd a while and then quick as a flash he showed me the refutation again. "So
>>>>>>>this guy is tough!", i concluded for myself. After the end of the game, we
>>>>>>>showed them what he had found. They were both surprised. Finally we were
>>>>>>>interested to see if there are any winningchances in the resulting QQ-endgame.
>>>>>>>Should i tell you who told us 19..Kc2 ? This is one of the few examples, there
>>>>>>>a skilled human can outperform current hard/software. If they can solve it all!
>>>>>>>I tried a few minutes with crafty, but gave up at the end. Can your computer
>>>>>>>come up with 1...Qxc4! ? Oliver Roese } 1...Qd6 ) 2.bxc4 Kd6 3.g4 ( 3.f4??
>>>>>>>exf4 4.gxf4 f5 -+ 5.Kg3 g6 6.Kh4 ( 6.h4 h5 ) 6...h6 ) 3...g6 4.Kf3 ( 4.Kg3?? Kc6
>>>>>>>5.f4 Kb7 6.fxe5 fxe5 7.Kf3 Ka6 8.Ke4 Kxa5 9.Kxe5 Kb4 10.Kd5 g5 -+ ) 4...f5
>>>>>>>5.gxf5 gxf5 6.Kg3 Kc6 7.Kh4 h6 8.Kh5 e4 9.Kh4 Kb7 10.Kg3 Ka6 11.Kf4 Kxa5 12.Kxf5
>>>>>>>Kb4 13.Kxe4 Kxc4 14.f4 Kb3! 15.f5 c4 16.f6 c3 17.f7 c2 18.f8=Q c1=Q = 19.Qb8+
>>>>>>>Kc2! 20.Qc7+ Kd1 21.Qxc1+ Kxc1 22.Kf5 Kd2 23.Kg6 Ke3 24.Kxh6 Kf4 1/2-1/2
>>>>>>
>>>>>>I think 3.Kf3! is a winner move. Black have no chances.
>>>>>>
>>>>>>1... Qxc4 2. bxc4 Kd6 3. Kf3!
>>>>>>
>>>>>>Paulo Soares, from Brazil
>>>>>
>>>>>But _why_ do you think that?
>>>>
>>>>I was wanting to place the answer quickly in the forum and I analyzed the
>>>>position believing in the evaluation of the program, without giving the
>>>>necessary time for a good evaluation. My mistake, sorry.
>>>>
>>>>1... Qxc4 2. bxc4 Kd6 3. Kf3 f5 {!}
>>>>4. g4 g6 5. gxf5 gxf5 6. Kg3 Kc7 7. Kh4 h6 8. Kh5 e4 9. Kh4 Kb7 (9... f4 10.
>>>>Kg4 e3 11. fxe3 fxe3 12. Kf3 {+-}) 10. Kg3 Ka6 11. Kf4 Kxa5 12. Kxf5 Kb4 13.
>>>>Kxe4 Kxc4 14. f4 Kb3 15. f5 c4 16. f6 c3 17. f7 c2 18. f8=Q c1=Q {=}
>>>>
>>>>Paulo
>>>
>>>The problem is that programs do not know to evaluate unstoppable pawns
>>>
>>>try the following position that can happen after
>>>3.Kf3 f5 4.g4 g6 5.gxf5 gxf5 6.kg3 Kc6 7.Kh4 h6 8.Kh5 e4 9.a6 Kb6 10.Kxh6 f4
>>>
>>>
>>>[D]8/8/Pk5K/2p5/2P1pp2/8/5P1P/8 w - - 0 1
>>>
>>>Programs cannot see at evaluation time that black is winning because of
>>>unstoppable pawn.
>>>
>>>If I give them to analyze at 1 ply depth they give a big advantage for white.
>>>
>>>part of the programs know that h2 is unstoppable but they do not know that e4 is
>>>unstoppable and that e4 can be a queen faster than h2
>>>
>>>Uri
>>
>>You can solve a problem in 2 ways, a) with chess knowledge or b) by search.
>>Very often search is much more powerful than adding complex and processor
>>time stealing complex chess knowledge. This position is a typical example
>>that search is the right solution to play the best move.
>>
>>Ed
>
>The problem is not this position but the position many plies before.
>
>programs did a mistake in the evaluation of the position many plies before
>probably because they did not give the right static evaluation to this position.
>
>I believe that it is important to see big positional scores at evaluation time
>because of this reason.
>
>Uri
Here is another test position that shows better the importance of knowledge
about passed pawns.
I composed this position
[D]Q3q3/4k3/8/5p2/2p5/8/P6P/4K3 w - - 0 1
avoid Qxe8+
Century1.2a(p450) can see in less than 5 minutes that Qxe8+ is losing but cannot
see a better move at least in the first 23 minutes.
I believe that a good evaluation can help to see that white is losing after 2
plies based on the squares of the pieces.
humans do not know it without search but humans do not have the best evaluation.
Uri
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