Jean-Marc Loustau (France)
 
#20 4+2

1 Bc5!
Threats 2 Bc4 (threats 3 Bxe6 and also 3 Bd5+ Kb8 4 a7+ and 5 a8=D) Re5 3 Kb6 (threats 4 Bd6 Rg5 5 Be6 Rf5 6 Bc8 Rb5+ 7 Kxb5 Ka7 etc.)                                                        
Rg5 8 Bd6 Re5 9 Bb3 (tempo) Rg5 10 Be6 etc.
1… Re5!
Rook must control e4 and f5 (if 1… Re8 or Re1 2 Bf5! etc.)
2 Kb6 Re6+ 3 Kc7
Always threatening 4 Bc4 : if 4… Re5 5 Kb6 Rg5 6 Bd6 etc.
3… Re8 4 Kd7!
Not 4 Bc4? Rc8+!! 5 Kd6 Rd8+ 6 Ke5 Kb8 with mate too late.
4… Re5!
Rook must continue to guard e4 but is dominated on file e : if 4… Re1? 5 Bd4!! Kb8 and for example 6 Bc2 Re2 7 Bb3 Re4 8 a7+ Kb7 9 Bd5+ Ka6                                                      10 Bxe4 with quick mate.
5 Kd6 Re8
If 5… Re1? 6 Bc4 Rd1+ (or Ra1) 7 Kc7 Rd2 8 Bb5 Rd7+ 9 Kxd7 and quick mate ; or 6… Kb8 7 a7+ Kb7 8 Bd5+ Ka6 9 a8=D+ etc.
6 Bg6!
Not 6 Bc4? Rd8+! as previously (a kind of Roman/anti-Roman).
6… Rd8+ 7 Ke7! Rg8!
Now Rook must stay on 8th rank (if 7… Rd2 or Rd1? 8 Be4+ Kb8 9 a7+ Kc7 10 a8=D Rd7+ 11 Ke6 for example, with quick mate). If 7… Rh8? 8 Be4+ Kb8 9 a7+ Kc7
10 Bd6+ Kb6 11 Bb8 Kc5 (if Black have played Rg8, then they would play here 11… Rg7+ ; here if 11… Rh7+?? 12 Bxh7 with quick mate) 12 a8=D Rxb8 13 Dxb8 etc.
If 7… Rc8?? 8 Be4+ Kb8 9 Bb6 (threats 10 a7#) Rc7+ 10 Bxc7 Kxc7 11 a7 Kb6 12 a8=D etc.
8 Be4+ Kb8 9 a7+ Kc7 10 Bd4! zugzwang
Not 10 Bd5!? Rh8! 11 Bd4 Rc8! and White don’t mate in 20 moves (reciprocal zugwang) !
Nor 10 Bd6+? Kb6 11 Bb8 Rg7+! 12 K plays Rxa7! (or 11 a8=D Rxa8 12 Bxa8 Kb5 13 Bd5 Ka4 with too late mate).
10… Rc8 11 Bd5! (zz) Rd8
Now Rook is completely dominated on 8th rank and will be captured.
12 Be5+
As previously 13 a8=D+? Rxa8 14 Bxa8 leads to a too late mate.
12… Kb6 13 Kxd8! Kxa7 14 Kc7 Ka6 15 Bc6 Ka5 16 Bc3+ Ka6 17 Bd7! Ka7 18 Bc8 Ka8 19 Bb7+ Ka7 20 Bd4#                                                                                                                                                                                                                                                                                                                     
2 Dominations of black Rook, first on file « e », then on 8th  rank (with zz).  Author