1... Sef5: 2.Sg6+ Ke4 3.Qd3+ Bd3:#
1... Shf5: 2.Sf7+ Ke4 3.Qd3+ Bd3:#
1.Qd3! ~ 2.Qe3+ Qe4 3.Qe4+ Be4:#
1... Sef5: 2.Sf7+ Sf7: 3.Qf5:+ Bf5:#
1... Shf5: 2.Sg6+ Sg6: 3.Qf5:+ Bf5:#
Reciprocal change based on necessity of forcing the BK to e4 in the set play and decoying the BS from guarding the square f5 after the key.[MV]
503. Milivoj S. Nesic Yugoslavia
s#3
10+12
1... d3 2.Bd2:+(A) Kd4: 3.Sb3+ Rb3:#
1... d5 2.Bd8+(B) Kd6 3.Sb7+ Rb7:#
1.Rb7! ~ 2.Qh2+ Kd5 3.Rb5+ Rb5:#
1... d3 2.Bd8+(A) Kd4: 3.Bb6+ Rb6:#
1... d5 2.Bd2:+(B) Kd6: 3.Bb4+ Rb4:#
Reciprocal change in a good position after withdrawal key.[ZG]
504. Victor Kolpakov Russia
s#4
b) BPh4-->h6
4+2
a) 1.Bf3 Kg3 2.Bg2 Kf2/h3 3.Be5(+) h3/Kf2 4.Bh2 hg2#
b) 1.Be1 h5 2.Bg4+ hg4 3.Bf2 g3 4.Bg1 g2#
Two good and completely different solutions with only 6 pieces on the board.[MV]
505. Vladan Vuckovic Yugoslavia
s#4v
5+4
1.Kh8? ~ 2.Qe7+
1... Kd8 2.Qd7+
1... 0-0-0+!
1.Re6+! Kd8 2.Re8+ Ke8: 3.Kh8!
Unusual logical maneouvre including black castling.[ZG]
1.g5! ~ 2.Rc6+/Bb6+
1... Bg5: 2.Rc6+ Kd5 3.Re6+ Kc5 4.Re5+ Re5:#
1... Rg5: 2.Bb6+ Kd6 3.Bd8+ Kc5 4.Be7+ Re7:#
1... Sc4 2.Sb7+! Kd5 3.Sd6+ Kc5 4.Se4+ Re4:#
Nowotny, white and black battery.[A]
Good harmony of thematic variations, but it would be much better if the variations appeared after black "Grimshaw".[ZG]