Friedrich Chlubna
A great composer can create an artistic problem from the simplest
theme, as this example illustrates.
1.Rg6 threat 2.Qg4+ Kxe5 3.Qe4;
1...Rg2 2.Rf6+ Kg3 3.Rf3;
1...Rf2 2.Qg5+ Kf3 3.Qg4;
1...Qd4 2.Qg4+ Kxe5 3.Qg5;
1...d5 2.Qg4+ Kxe5 3.Re6;
1...e2 2.Qg5+ Kf3 3.Qg3.
The selfblock, where a piece prevents a king from moving to a
flight square, is one of the simplest problem ideas. More
subtle is the anticipatory selfblock, where a piece blocks a
square then the king is driven towards the blocker. The five
defences in Chlubna’s elegant problem are all anticipatory
selfblocks.
Dafydd Johnston: Five distant self-blocks is an amazing
achievement with so few pieces. Clever use of the white king to
enable the Rf2 defence.