Thursday, February 22, 2007

Something Entirely Different

When I in 1977 as a 13-years old boy first visited Kongsvinger Sjakklubb, one of the first sights that met me, was a group of adult players discussing whether it really was possible that this position could occur after only 4 moves:

I happily joined in with my suggestions but after 30 minutes of heavy thinking and discussion and a lot of aimless moving around, we concluded that it was impossible: The two knights simply could not both capture each other and it was not time for other pieces to capture them and return to its original squares.

Well, it turned out that it was possible after all, but only after the person who had offered the puzzle (standing sniggering in the background all the time) demonstrated the solution. Since that day I have had a fascination for this kind of retrograde puzzles, and collected whatever I have come across. Unfortunately the composer (originator/creator?) of the puzzle very rarely is provided.

Sometime around 2000, I was offered this seemingly related puzzle:

Can this position occur after only 5 moves? Surprisingly knowing the solution to the previous puzzle does not make it easier at all.

Judging from the reactions to puzzle No 7 at the
ChessBase Christmas Quiz, I am not the only chess-player fascinated by this kind of useless brain exercizes. You can safely look at the readers' feedback - all spoilers have been removed.

I will return with solutions (also for the ChessBase nut, which is quite hard) in a few days.

Frustrated Note:
It seems that I cannot add a link to the ChessBase Christmas Quiz. I have no idea why, but here it is as a text string:

If you want to solve the puzzles yourself, be careful. I will allow spoilers in the Comments below (they will become visible if you open a post by clicking the header or if you click the "Comments" link below).


Anonymous said...

Got the first puzzle: 1.Nf3 d6 2.Ne5 Nf6 3.Nc6 Nfd7 4.Nxb8 Nxb8.

The trick was envisioning the position with wN@c6 and bN@d7 then realizing this position could be reached in three moves.

Sverre Johnsen said...

Well done!

I hope I will not have too many angry readers because of this spoiler. I will post a warning in the main entry.

Anonymous said...

I got both puzzles!

For me the way I found both solutions was to look at the possible alternatives for how the final capture was achieved.

Since there are so few moves at our disposal there obviously isn't time for a piece to make a wasted move and then return to its original position (to cloud the issue of how the position occured)

In the first puzzle it's not possible for the d6 pawn to have been a part of any capture, thus the only possible locations for the final capture are b2 and b8. Therefore the sequence stated above must be the solution.

In the second puzzle, there are no knights left at all. This made things easier. The final capture had to have been of a white knight conducted by the pawn that ended up on d5. This means that the same pawn must have captured the other white knight on either c6 or e6, and the rest is simple.

1.Nf3 Nc6 2. Nd4 Nf6 3.Nxc6 dxc6 4.Nc3 Nd5 5.Nxd5 cxd5