Men, Martians and Machines December 27, 2005
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Help for helpmate novices

Viktor Zheglov, Suomen Tehtaevaeniekat 1998-99

Helpmate in 12 (Black to play helps
White to deliver mate in twelve moves)

Long helpmates are all a question of logic. In the above case the black king can only be mated in a corner, and for this he needs to promote his pawn to a knight. Can he be mated on a8? Then the knight would have to be on a7 or b8. It takes too long to reach b8 (this requires 13 black moves in total).

But a7 looks possible. It takes 11 moves for Black to reach a position with king on a8 and knight on a7. However, White’s king must be on c7 in this position, which is currently controlled by Black’s queen. Therefore, Black’s spare move must be used to play his queen away from the control of c7. This should at once arouse our suspicions, for there is no obvious reason why the queen should play to one square and not another. Indeed, if we look a little closer we can see that White’s last move must be either Ba6-b7# or Bc8-b7#, with the WK already on c7. But Black’s previous move must be ...Nb5-a7 (the knight can only reach a7 from b1 in 3 moves via b5), and on b5 the knight would have checked the white king.

Thus the mate must be on h1. The black queen controls g3, so we cannot have black king on h1 and black knight on g1.

The mating position must be as shown on the right, with Bh3-g2# or Bf1-g2# as the mating move. At first sight this is easy as White plays Bd5, Kd7-c6-b5-c4, Be4, Kd3-e2-f2 and Be6-h3-g2 for a total of 12 moves, while Black arranges his king and knight.

But there are problems. The easiest way to find out is to load the starting position in Fritz or ChessBase and then try to execute the mate while making only legal moves. It is not as easy as you might expect.

You probably know that you can click on "File – New – Position setup" (or simply press 'S') to enter a new position. You can also copy one of the following strings and then use "Paste ASCII" or "Paste FEN" in the Setup screen to enter them with one click:

wKc8,Bb7/bKb3,Qe5,Pb4

2K5/1B6/8/4q3/1p6/1k6/8/8 b - - 0 1

Once you have found all the right moves you will recognize the true beauty of the problem. This lies in the remarkable fact that the order of all the moves is uniquely determined.