[Retros] Original by Kari Karhunen

[Francois Labelle]

Correction:

I should have said

"
White is afraid of
1. ?? Na6 2. a4 Nb4 3. d4 c6 4. Ra3 Qa5 5. Rd3 Nxd3#
*and*
1. ?? Na6 2. *h4* Nb4 3. d4 c6 4. *Rh3* Qa5 5. Rd3 Nxd3#
"

otherwise 1. Na3 or 1. b3 block the rook's path.

Anyway what's nice about this problem is that to solve it one must find 
at least 4 different ways to mate with NxR, solving in particular the 
Christmas puzzle (1. e4), and it doesn't suffer from the fact that the 
solution to 1. e4 (and to other moves) is not unique.

     François


On 09/20/2013 04:58 PM, Francois Labelle wrote:

> Solution:

>

> White is afraid of

> 1. ?? Na6 2. a4 Nb4 3. d4 c6 4. Ra3 Qa5 5. Rd3 Nxd3#

>

> The only moves that avoid this are:

> 1. Nc3

> 1. c3

> 1. e3

> 1. e4

>

> Three of these moves can still lead to 5... NxR#:

> 1. Nc3 Nf6 2. Nd5 Ne4 3. Nxe7 Nxf2 4. Nc6 Qh4 5. g4 Nxh1#

> 1. c3 Nc6 2. h4 Nd4 3. Rh3 Nxe2 4. Rd3 Nxc1 5. Ne2 Nxd3#

> 1. e4 Nf6 2. Qe2 Nxe4 3. f3 Ng3 4. Qxe7+ Qxe7+ 5. Kf2 Nxh1#

>

> So by elimination the first move must be

> 1. e3

>

> My computer confirms that 1. e3 ... 5... NxR# is impossible, so the 

> problem is C+. Nice problem!

>

>     François

>

>

> On 09/18/2013 09:12 AM, Olli Heimo wrote:

>> Hi! I showed some our discussions to Kari Karhunen. He is IM in 

>> solving and he suggests the following problem claiming that it is 

>> sound. I have not yet solved it. Olli. Solutions please.

>>

>> Kari Karhunen, original for retro mailing list.

>> White wants to avoid any possibility that the game ends with 5. - NxR#.

>> Which was the first move by White.

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