a) diagram
1.Qh3! zugzwang.
1...Kd4 (a) 2.Se5 threat: 3.Qd3# 2...Ke4 3.Qf3+ Kd4 4.Qd3#
1...Kf4 (b) 2.Se5 zz. Kg5 3.Qg4+ Kh6 4.Qg6# (mm) 3...Kf6 4.Qg6#
2...Ke4 3.Qf3+ Kd4 4.Qd3#
b) wSf7 → e6
1.Kc5! zugzwang.
1...Ke3 (c) 2.Sd4 zz. Kd2 3.Qe2+ Kc1 4.Qc2# (mm) 3...Kc3 4.Qc2#
2...Ke4 3.Qf3+ Ke5 4.Qf5#
1...Ke5 (d) 2.Sd4 threat: 3.Qf5# 2...Ke4 3.Qf3+ Ke5 4.Qf5#
c) wSf7 → d1
1.Kc6? zugzwang.
1...Kd4 (a) 2.Qf5 (A) threat: 3.Qd5# 2...Kc4 3.Qb5+ (B) Kd4 4.Qd5#
but 1...Ke5!
1.Ke6! threat: 2.Qf5+ Kd4 3.Qd5#
1...Kd4 (a) 2.Qb5 (B) threat: 3.Qd5# 2...Ke4 3.Qf5+ (A) Kd4 4.Qd5#
