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Posted by ganstaman
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5/04/2008
08:11:43

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Subject: Puzzle 283

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Ok, the puzzle on the homepage at the time of me writing this (search for puzzle number 283 here: gameknot.com )



White to move, mate in 4. I won't spoil the solution given, as it is brilliant seeming to me.

But how can black spoil white's plan of Qh4-(h or e)7-b7#? I can see black delaying the journey by 1 move, so it would be mate in 4. What did I miss, if anything?


Posted by heinzkat
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5/04/2008
08:21:53

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I think the answer is

Message:
1. Qh4 Rh1!

Posted by sf115
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5/04/2008
08:35:09

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If 1. Qh4 Rh1 white either:

2. Qxh1 a1=Q 3. Qh7 Qxa6+ 4. bxa6 b1=Q 5. Qb7++ which is a move slower than the actual solution.

OR

2. continue with the original plan with 2. Qe7 Rh8+ 3. Nd8 Rh7 (3...Rxd8 also slows down whites mate) 4. Qb7+ Rxb7 5. axb7++ which is also in 5 moves.

So there is only a mate in 5, which is slower than the actual solution
———
Endgames, part 1: Rook against Bishop — A superb lesson from Magnus Carlsen in endgame technique. It's been a while since we looked at the endgame, so this week we begin a short series on this often neglected area with a terrific demonstration of endgame technique from the ever-improving chess world No 1 Magnus Carlsen. Although White has the advantage of rook against bishop, Black has an extra pawn and a solid position on the chess board. How did Carlsen make progress? RB I'm pretty sure the answer lies in g4. The question is whether to nudge the pawn forward immediately or whether some preparation is needed first, perhaps exchanging on d5 or advancing the king to e3. The only way is concrete calculation, so let's see what ...
Posted by ganstaman
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5/04/2008
09:50:31

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Ah, that seems to do it. Thanks.
———
Dortmund Begins — The Sparkassen Chess-Meeting (an odd name, to be sure) began Thursday in Dortmund. Though the chess tournament is not at the level of Linares or Corus, it still attracts top players, notably Vladimir Kramnik, the former world chess champion from Russia. Kramnik has been associated with Dortmund, as the chess event is often referred to, for many years because he has won the tournament nine times, far more than any other. He first won it in 1995 and is the defending champion this year. The tournament is a double-round robin this year, meaning each competitor plays all the others twice, once with each color. In addition to Kramnik, the No. 4 chess player in the world, the field includes ...
Posted by lighttotheright
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5/05/2008
03:53:48

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There is an alternate solution that is not accounted for by this puzzle. This kind of thing irritates me. It turns out that my first choice was in fact correct, but the puzzle said I made a mistake. Once you know the solution, it is easy to see that my alternate path works because mine is based on the same principles that are used in the given one.

It's still mate in four, but why are alternate solutions unaccounted for? I thought that problem was fixed long ago.
———
Zhao and Zatonskih Lead Chess Championships — Anna Zatonskih, the defending chess champion, took the lead of the U.S. Women’s Championship on Wednesday, while Parker Zhao, the ninth seed, solidified his grip on the U.S. Junior Championship. The two chess tournaments are being held concurrently at the Chess Club and Scholastic Center of Saint Louis. Zatonskih had shared the lead for the last few rounds with Irina Krush, the top seed. But in Round 5 on Wednesday, Zatonskih beat Iryna Zenyuk, while Krush only drew against Camilla Baginskaite. Zatonskih now leads with 4.5 points, while Krush and Tatev Abrahamyan, who beat Abby Marshall on Wednesday, have 4 each. In the junior championship, Zhao, who ...
Posted by heinzkat
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5/05/2008
04:22:15

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That problem was fixed long ago

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Lighttotheright, I think you're wrong here though - puzzle 283 has only one solution (for mate in four).
———
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Posted by lighttotheright
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5/05/2008
04:33:40

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The alternate 1. Nd8 works and is confirmed. It is mate in four just like the given solution.
———
Fast Pace Continues at Two U.S. Chess Championships — The top two seeds in the U.S. Women’s Chess Championship could make no headway against each other and drew their Round 3 game on Monday. But their two nearest competitors lost, so Irina Krush and Anna Zatonskih now lead the chess tournament by half a point over Tatev Abrahamyan, Alisa Melekhina (who lost to Abrahamyan on Monday) and Iryna Zenyuk, who lost on Monday to Beatriz Marinello. In the U.S. Junior Chess Championship, which is being held concurrently at the Chess Club and Scholastic Center of Saint Louis, Warren Harper, the seventh seed, is the surprising leader after three rounds with a perfect score. His play so far has been stellar and on Monday he demolished his ...
Posted by lighttotheright
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5/05/2008
04:38:41

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Heinzkat -- I'm not wrong. 1. Nd8 does work. The problem is that no computer can solve this particular problem from four moves out. The computer checking the solutions is wrong.

Once you input the solution, the computer suddenly sees the solution at 2 or 3 moves out depending upon the program that you use. This particular puzzle is an anti-computer one.


Posted by heinzkat
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5/05/2008
04:47:30

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Lighttotheright!

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This is the interesting part of the puzzle, which is not covered in puzzle #283, since the puzzle application didn't support underpromotions of the opposite side back then. After 1. Nd8? [if I may boldly give it a ?] c2
2. Qc1 b1=B! Black is stalemated and there can be no mate in four.

After 1. Nb4 however, 1. ... c2 2. Qc1 b1=B 3. Nd3! exd3 4. Qh1, it IS mate in four :-)


Posted by chessnovice
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5/05/2008
04:48:12

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...

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Sometimes puzzle makers don't have solutions entered entirely. Human error is prone to omissions. If you find an alternate solution, you're able to enter it. Nothing to necessarily get irritated about, I think.

Posted by heinzkat
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5/05/2008
04:55:26

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Also...

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Remember GameKnot does no checking of the puzzle at all - the puzzle application merely checks if all variations end in checkmate. If so, the puzzle is 'approved' 'correct' (twice '', ah well) an can be put up for others to solve. As you can see on the puzzle page, a lot of the puzzles still have some hiatuses then. If you think 1. Nd8 mates in four too, 'prove it'! You can do so by browsing to puzzle #283, hover over 'Options' in the right corner and click 'Alt. solution...'. This will give you the option to prove there is another way to play, that results in mate in at most the same number of moves as the original author. If all variations are correct, you can save the puzzle too, and the puzzle has been 'improved'.

Posted by lighttotheright
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5/05/2008
04:58:36

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Message:
1. Nd8 c2 2. Qc1 b1=B 3. Nd5 Qb2 (or any move) 4. Nc7#

It is forced checkmate. There is no stalemate with my solution. The alternate is confirmed, and not seen by computer at four moves out.


Posted by lighttotheright
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5/05/2008
05:00:17

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Message:
1. Nd8 c2 2. Qc1 b1=B 3. Nd5 Bb2 (or any move) 4. Nc7#

Sorry I made a slight error in copying the line. This is correct.


Posted by heinzkat
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5/05/2008
05:01:19

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2. ... b1=B!

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Not 2. ... b1=Q. Please re-evaluate your assessments. :-)

(note that I hadn't noticed the b1=B solution either. A nice brilliancy by Ado Kraemer)


Posted by heinzkat
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5/05/2008
05:02:30

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Lighttotheright

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3. ... Bb2 is not possible in the intended line! It's 2. ... b1=B, not 2. ... bxc1=B.

Posted by lighttotheright
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5/05/2008
05:03:18

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Message:
I did it again.

1. Nd8 c2 2. Qc1 b1=B 3. Ne6 Bb2 (or any move) 4. Nc7#

Those knight moves can get confusing.

I think this is correct now.


Posted by lighttotheright
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5/05/2008
05:06:00

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Message:
Heinskat look at the position. The key to the solutiion is the knight path. The Queen sac is to block any defence by black. The solution is very simple. 1. Nb4 and 1. Nd8 both work.

Posted by heinzkat
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5/05/2008
05:06:23

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Note that in your line...

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3. ... Bb2 is illegal. In fact, after 3. Ne6, all Black's moves are illegal - it is stalemate!

Posted by heinzkat
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5/05/2008
05:09:59

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OK... with a diagram then...

Message:
After
1. Nd8 c2
2. Qc1 b1=B
3. Ne6
It is Black to move. Do you see any legal ones?



Interesting how Ado Kraemer can still keep us busy with his brilliant problems, 36 years after he died.


Posted by lighttotheright
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5/05/2008
05:14:36

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Message:
OK heinzkat. You threw me for a loop with b1. I was thinking about the c1 square. But even with b1=B, it is still checkmate in four. 1. Nd8 b1=b 2. Qxc3 and my solution still works.



Posted by heinzkat
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5/05/2008
05:21:11

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Well...

Message:
1. Nd8 c2
2. Qc1 b1=B is the line that makes mate in four impossible.

1. Nd8 b1=B like you give in this last post, perfectly mates in four - but there's a difference. Carefully check the notations right from the beginning of this thread, I think I haven't messed up any of them...


Posted by lighttotheright
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5/05/2008
05:21:54

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Message:
OK...It is still not stalemate. But it would be a mate in 5 instead. 1. Nd8 c2 2. Qc1 b1=B 3. Qxc2 and it is not stalemate. ...but it does take an extra turn to get the knight to c7.

Posted by lighttotheright
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5/05/2008
05:24:17

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Sorry for some of the copy mistakes. My copy function on my computer is not working. I have to reboot my whole computer to correct the problem.

Posted by heinzkat
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5/05/2008
05:24:20

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Exactly...

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And therefore, 1. Nd8 is an incorrect try. Mate in five is possible in many ways - there is only one correct starting move to mate in four.

Posted by lighttotheright
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5/05/2008
05:58:50

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Message:
Well, it looked correct to me at the time. And my computer was not cooperating with me either!

Posted by chessnovice
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5/06/2008
13:55:37

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...

Message:
b1=B is pretty clever! Indeed, prolongs the Nd8 line by one move. I wouldn't worry about not considering that though, since I doubt that very many people really would.

Posted by bogg
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5/06/2008
15:13:15

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In case anyone else has the ...

Message:
same problem that I had. The reason that 2. ... b1=B doesn't cook 1.Nb4 and does cook 1. Nd4 and 1. Nd8 is because after 1.Nd4 White has 3. Nd3 ed: 4. Qh1++.

Took me a while to see the tree within the forest.
CTC


Posted by heinzkat
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5/07/2008
01:30:09

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chessnovice

Message:
Obviously the composer did consider it :)

bogg: indeed, see my post above too, 5/05/2008 04:47:30


Posted by chessnovice
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5/07/2008
01:44:28

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hienzkat

Message:
True. But if you can't trust the composer, who can you trust?

Posted by bogg
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5/07/2008
06:35:06

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heinzkat

Message:
Missed that post. Would have saved me some time had I noticed it.

CTC