Mate in 9

#9

Well I can't say for sure without looking it more closely but my sympathies are with 1.Nf5!?

bump

Originally posted by BigDoggProblem
R. Albrecht, Deutsche Schachblatter 1980
[fen]1b1Kn3/k5N1/2Qp1p2/3p4/pN1p4/6P1/r6p/4Bq2 w - - 0 1[/fen]
#9

This is a difficult, yet beautiful problem, so I am not surprised nobody solved it.

The key is to use short threats. White's main threats are Qb7 or Qa6. Watch how the black Queen works overtime trying to stop the inevitable:

1.Kc8 Qh3+ 2.g4!
The first diversion.
2...Qxg4+ 3.Kd8 Qe2 4.Bf2
The point of the first diversion is revealed. The bQ interferes with Ra2, preventing the reply 4...Rxf2.
4...Rd2 5.Kc8 Qg4+ 6.Nf5!!
The second diversion, with the same interference idea.
6...Qxf5+ 7.Kd8 Qd3 8.Bxd4+
And now the bQ is again interfering with the Rook.
8...Qxd4 9.Qa6#

How do you answer 1...Qc4?

Originally posted by THUDandBLUNDER
How do you answer 1...Qc4?

An excellent question.

I could not see a mate and my book doesn't give this line and I triple-checked the diagram. It matches the book. My solving program confirms no mate in 8 after 1...Qc4. So it's no wonder nobody solved it. I apologize to those who have spent time on this.

I will investigate and try to determine where the error is. It will be difficult since the book is likely in error.

Originally posted by BigDoggProblem
An excellent question.

I could not see a mate and my book doesn't give this line and I triple-checked the diagram. It matches the book. My solving program confirms no mate in 8 after 1...Qc4. So it's no wonder nobody solved it. I apologize to those who have spent time on this.

I will investigate and try to determine where the error is. It will be difficult since the book is likely in error.

Unfortunately, I have not been able to find Albrecht's problem online. Nor can I determine how to correct the problem (this would take someone who has more skill composing directmates!).

Perhaps there is a white pawn missing on b3?

Originally posted by ilywrin
Perhaps there is a white pawn missing on b3?

Finally! I believe I've found the error. Add a black pawn on c7, and the position is:

#9

And my solving program confirms 1.Kc8! is the solution, with the main line as given previously. Now all that's left is to verify that there aren't any other solutions.

Originally posted by BigDoggProblem
Finally! I believe I've found the error. [b]Add a black pawn on c7, and the position is:
[fen]1b1Kn3/k1p3N1/2Qp1p2/3p4/pN1p4/6P1/r6p/4Bq2[/fen]
#9

And my solving program confirms 1.Kc8! is the solution, with the main line as given previously. Now all that's left is to verify that there aren't any other solutions.[/b]

After 6 and a half hours, the program confirms 1.Kc8! is the only solution.