[Retros] =N double checkmates

[raosorio at fibertel.com.ar]

Hi Hiro,

I understand that you are listing the double check cases showing ...=N#.
The following PG was published in Strategems first 2007 issue. It's the
g2-g1=N case, standard material since the promoted knight is a Phenix one.

Roberto Osorio - Argentina
Strategems 1st 2007
Dedicated to Andrey Frolkin
6sr/pp1qp3/1pk5/5p2/8/4P2b/PPPPK2r/RSBSQBsR
30 single moves. 13 + 12     C+

 Solution
1.Pf2-f4   Ph7-h5   2.Pf4-f5   Ph5-h4   3.Pf5-f6   Ph4-h3   
4.Pf6xg7   Ph3xg2   5.Pg7xf8=S Rh8xh2   6.Sf8xd7   Sg8-h6   
7.Sd7xb8   Bc8-h3   8.Sb8-d7   Pf7-f5   9.Sd7-b6   Pc7xb6   
10.Pe2-e3   Ke8-d7   11.Sg1-e2   Kd7-c6   12.Se2-c3   Qd8-d7   
13.Ke1-e2   Ra8-h8   14.Qd1-e1   Sh6-g8   15.Sc3-d1   Pg2-g1=S 

Best,
Roberto