Section A1 – Win
The rook is attacked and the king is in check. How can White win?
1.Ng6+!
Everything else leads to a draw:
( 1.Rg6? f2! 2.c7! f1=Q
( 2…Bxg6+ 3.Nxg6+ Kd7 4.Ne5+ Kxc7 5.Nd3+ =, quiet )
3.c8=Q Qg2+ 4.Kxb1 Bxg6+ 5.Nxg6+ Qxg6+ =, quiet )
( 1.Rd3? f2 2.c7 f1=Q 3.c8=Q Bxd3+ 4.Nxd3 Qe2+ =, quiet )
( 1.Nd3? f2 2.c7 f1=Q 3.c8=Q Bxd3+ 4.Rxd3 Qe2+ 5.Kxb1 Qxd3+ =, quiet )
1…Bxg6+ 2.Rxg6
( 2.Kc1? f2 3.Rd1 Nc3 4.Rf1 Ne4 5.c7 Bf5 =, quiet )
2…f2!
The passed pawn gives Black a chance to escape. For the pawn, White will have to give up the rook.
3.Rg7+!
( Try: 3.Bd6+? Kf7! 4.Rg4 f1=Q 5.Rf4+ Qxf4 6.Bxf4 Na3+ 7.Kb3 Nb5 8.Kc4 Na7! 9.c7 Ke7 10.Kc5 Kd7 11.Kb6 Nc6! 12.Kb7 Nd8+ 13.Kb8 Nc6+ =, quiet Perpetual check )
( Or 3.Rg4? f1=Q 4.Re4+ Kf6 5.Rf4+ Qxf4 6.Bxf4 Na3+ 7.Kb3 Nb5 8.Kc4 Na7 =, quiet )
( 3.Rg1? fxg1=Q 4.Bxg1 Kd6 =, quiet )
3…Kf8!
( 3…Kf6 4.Be5+!
( 4.Rg8 Kf7 )
4…Ke6 5.c7 f1=Q 6.c8=Q+ Kxe5 7.Re7+ +- )
4.Rg1!
( 4.Rg4? f1=Q 5.Rf4+ Qxf4 6.Bxf4 Na3+ 7.Kb3 Nb5 8.Kc4 Na7 =, quiet )
4…Na3+ 5.Kb3 fxg1=Q 6.Bxg1
A change in the situation! Now the white passed pawn gives a chance to win.
6…Nb5 7.Kc4!
( 7.Kb4? Nc7 8.Bh2 Ne6 =, quiet )
7…Nc7 8.Bb6!
( 8.Bh2? Ne8! 9.Kb5 Ke7 =, quiet )
8…Ne8 9.Bd8!
( 9.Bc5+? Kf7 10.Kd5 Nc7+ 11.Kd6 Ne8+ 12.Kd7 Nf6+ 13.Kd8 Nd5 =, quiet )
9…Nd6+ 10.Kd5!
( 10.Kc5? Ke8! 11.Bb6
( 11.c7 Kd7 )
( 11.Bh4 Nc8 =, quiet )
)
10…Ke8 11.Ke6!
Refusal to take the knight due to the position of mutual zugzwang.
( 11.Kxd6? Kxd8 Reciprocal zugzwang WTM 12.c7+ Kc8 13.Kc6 =, quiet Stalemate. )
11…Nb5!
Black refuses to take the bishop for the same reason.
( 11…Kxd8? 12.Kxd6 Reciprocal zugzwang BTM 12…Kc8 13.c7 Kb7 14.Kd7 +- )
12.Bb6!
( 12.Bf6? Nc7+ 13.Kd6 Nb5+ 14.Kc5 Na7 15.c7 Kd7 =, quiet )
12…Kf8 13.Kd7
( 13.Bc5+ Ke8 14.Bb6 Kf8 )
13…Kg8 14.Ke8!
( 14.Bd4 Kf8 15.Bb6 Kg8 )
14…Nd6+ 15.Kd8 Nb5 16.Bc5!
( Waste of time: 16.Ke7 Kg7 17.Ke6 Kf8 18.Kd7 Kg8 19.Ke8 )
( Or 16.Ke8 Nd6+ 17.Kd8 Nb5 )
16…Kf7 17.Kd7!
Reciprocal zugzwang BTM
( 17.Kc8? Nc3 18.Kd7
( 18.Kb7 Nd5 =, quiet )
18…Nb5 =, quiet Reciprocal zugzwang WTM )
17…Kf6 18.Kc8! Ke6
( 18…Nc3? 19.Bd4+! )
19.Kb7 +-
e.g.
19…Kd5 20.Be7 Kc4 21.Bf8 Kd5 22.Kb6 Kc4 23.Bg7 Kb4 24.Bh6 Kc4 25.Bd2 Nd6 26.c7 +- 1-0