The Czech composer Vladimir Pachman showed great skill in combining model
mates with strategy. Even this simple looking position illustrates a clever
reciprocal theme.
Solution: 1.f4? threatening an immediate mate by 2.fxg5, looks strong, but
White has no continuation after 1...Bh4 (2.c6? gxf4!). The key is 1.f3,
threatening 2.Bxg5+ Kxg5 3.Qf6, against which Black has two defences.
1...Bh4 allows 2.Qg8, placing Black in zugzwang and compelling the bishop to
abandon g5, after which 3.Bxg5 mates. This works because the bishop prevents
the pawn from moving to h4. After 1...h4 2.f4 now works because the pawn
prevents the bishop from moving to h4. The only defences to the threatened
3.fxg5 are 2...gxf4 3.Bxf4 and 2...g4 3.f5.