Chess problem

A chess problem, formally called a chess composition, is a puzzle set by somebody using chess pieces on a chess board, presenting the solver with a particular task to be achieved. For instance, a position might be given with the instruction that white is to move first, and checkmate black in two moves against any possible defence. A person who creates such problems is known as a "composer". There is a good deal of specialised jargon used in chess problems; see chess problem terminology for a list.

Example problem

To the right is a problem composed by T. Taverner in 1881. It is a directmate, with white to move and mate in 2.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The key move is Rh1. This is difficult to find because it makes no threat -- instead, it puts black in zugzwang, a situation where every move is worse than no move, yet the player has to move anyway. Each of black's nineteen legal replies allows an immediate mate. For example, if black defends with 1...Bxh7, the d5 square is no longer guarded, and white mates with 2.Nd5#. Or if black plays 1...Re5, he blocks that escape square for his king allowing 2.Qg4#. Yet if black could pass (i.e. make no move at all) white would have no way to mate on his second move.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The thematic approach to solving is then to notice that in the original position, black is already almost in zugzwang. If black were compelled to play first, only Re3 and Bg5 would not allow immediate mate. However, each of those two moves blocks a critical escape square for the black king (a flight square), and once white has removed his rook from h2 he can put some other piece on that square to deliver mate: 1...Re3 2. Bh2# and 1...Bg5 2.Qh2#.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The arrangement of the black rooks and bishops, with a pair of adjacent rooks flanked by a pair of bishops, is known to problemists as Organ Pipes. This arrangement means the black pieces get in the way of each other: for example, consider what happens after the key if black plays 1...Bf7. White now mates with 2.Qf5#, a move which is only possible because the bishop black moved has got in the way of the rook's guard of f5 - this is known as a self-interference. Similarly, if black tries 1...Rf7, this interferes with the bishop's guard of d5, meaning white can mate with Nd5#. Mutual interferences like this, between two pieces on one square, are known as Grimshaw interferences. There are several Grimshaw interferences in this problem.

Related Topics:
Organ Pipes - Grimshaw

~ ~ ~ ~ ~ ~ ~ ~ ~ ~