02 March 2011

Colours

Today, we'll have a look at colouring problems. No, we won't paint chess pieces in blue, red or any other colour — except black and white and even then only virtually. This kind of chess problems has been invented by Albert H. Kniest. In 1964, he published an article on the topic in Diagramme und Figuren. In a colouring problem, you have a position where you don't know (yet) of which colour the pieces are. You only know that they are either black or white and that the position is legal.

Gideon Husserl
feenschach 1986
[6KQ/8/6RK/8/8/8/8/8]
Colour the pieces
a) Diagram
b) Rg6 → g7
  Let's have a look at an example (see diagram). Obviously, in a), one of the kings is in double check by the rook and the queen. Otherwise, both kings were in check simultaneously and that is illegal. The double check can only be explained by the promotion g7xh8=Q+. Therefore, Kh6, Qh8 and Rg6 are white, Kg8 is Black.

In b), only the queen gives check to one of the kings. There is just one last move which leads to this position, namely h7-h8=Q+. From there, we see that Kg8 and Rg7 (and Qh8) have to be white, Kh6 is black.

That was no big deal, right? The next problem should be a little bit more challenging.

Gideon Husserl
Israel Ring Tourney 1966-1971
Prize
[B1KRN3/PP6/2QK1R2/8/8/8/8/8]
Colour the pieces. Last move?
  Here, one of the two kings is in double check by Rd8 and Qc6. As we already have seen in the previous problem, the only possible explanation is a promotion: c7xd8=R+. So, we conclude that Rd8, Qc6 and Kd6 are white and Kc8 is black. Furthermore, to exclude illegal checks, Ne8 and Rf6 have to be white and Pb7 black. As there is a black pawn on b7, the Ba8 has to be white. Pa7 is also white to allow the promotion into wBa8. The last move was c7xNd8=R+ because only a Nd8 gives Black the opportunity to retract a move (Ne6-/xd8).

Still not thrilling enough? Good, here's something to keep you busy for quite some time.

Henrik Juel
Thema Danicum 07/2004
 
[8/3PPPP1/4P3/3PPP1P/4P3/K2PPK1P/1P2P1P1/8]
Colour the pieces

Dmitri Baibikow
Schachmatnaja komposizija 12/2008
2nd Prize
[2K1K3/PPPPPPPP/1PP1P3/PPPP4/1P6/8/8/8]
Colour the pieces. Last two half-moves?

Did you actually solve at least one of the problems? Congratulations. If not, I hope you tried at least. Anyway, here are the solutions.
Juel: Kf3 and Pd3,d5,d7,e4,e7,f5,g2,h3 are white, the rest black.
Baibikow: Ke8 and Pa5,b6,c5,c6,d7,e6,e7,f7 are white, the rest black. Last moves were d6-d7+ Kb8-c8.

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