## Saturday, May 24, 2008

### Selfmates (2)

We continue with selfmates, in which White plays and forces Black to give checkmate, while Black is resisting to do so.

 (Problem 92) W. Jørgensen, First Prize, ”Die Schwalbe“, 1952 (White plays and forces black to mate in 3 moves). Selfmate in 3 s#3 (14+11) [2b2Ksq/RP1BP1rr/7b/4p1p1/1S2k1P1/3s2P1/1pQPP3/SR4B1]

There are three tries: {1.e8=Q? bxa1=Q!}, {1.Bf5+? Bxf5!}, {1.exd3+? Kf3!}.
Key: 1.e8=B! (zugzwang)

If 1...bxa1=Q 2.bxc8=S Qd4
(in any other place the Qa1 is captured, and the black move checkmates)
3.Sd6+ Qxd6#.

If 1...bxa1=R 2.bxc8=B Ra6
(in any other place the Ra1 is captured, and the black move checkmates)
3.Bxa6 (and black move will checkmate. Not 3.Rxa6? because, after Re7+, the Ra6 can capture the Bh6).

If 1...bxa1=B 2.bxc8=R Bd4
(in any other place the Ba1 is captured and the black move checkmates)
3.Rc4 (and black move will checkmate).

If 1...bxa1=S 2.bxc8=Q Sxc2 / Sb3
3.Qxc2 / Rxb3 (and black move will checkmate).

In problem-92 we have seen double allumwandlung and capture of the promoted black piece in the third move.

 (Problem 93) Nikolai Argunow ”Schachmatnaja Komposizija”, 07-08/1999 (There is set play). Selfmate in 2. * s#2 (11+8) [2S2bBR/4P1k1/7p/2S2p1P/3p1P2/1PpP4/2Kp4/1s1R4]

Phase (set play) : (*)
1...Kxh8 2.exf8=Q Sa3#
1...Kf6 2.exf8=B Sa3 #

Phase (actual play) : Key: 1.Se6+!
1...Kxh8 2.exf8=R Sa3#
1...Kf6 2.exf8=S Sa3#

Composer Argunow achieves the four promotions on square f8, (Theme Allumwandlung), in two phases. The checking key is not considered a defect for a selfmate.

(This post in Greek language).