Chess Problems: Obstruction!
5/29/2012 – In his last column
problem expert David Friedgood explained the self-block, which is a special
case of today's theme: obstruction. This occurs when a piece moves to a square
so that another piece is prevented from occupying it. We are given
two examples that show the basic idea – one with three beautifully engineered
variations – and two problems to solve. An entertaining challenge.
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Chess Problems: Obstruction!
By David Friedgood
“Obstruction occurs when a piece moves to a square so that another piece is prevented from occupying that square” (Chess Wizardry: The New ABC of Chess Problems, by John Rice, B.T. Batsford 1996). It is clear from this definition that the self-block, which my last series of articles explored, is really a special case of obstruction, in which a flight square in the king’s field is blocked. In a two-mover, the self-block of the king is the only type of obstruction that is feasible, so we will be dealing with three and more-movers from now on.
Let us look at some problems exemplifying obstruction. The first shows the basic idea repeated in three beautifully engineered variations on the theme:
The second problem, a four-mover, shows mutual obstruction on the same square between two pieces, harking back to the similar Grimshaw theme:
Now I leave you with two obstruction-themed problems for solving, the annotated solutions to which will appear in a while. In both cases you have to find the unique key move which contains a threat of forcing mate on the third move. You have to find Black’s defences to the threat and the continuations whereby White takes advantage of the new weaknesses arising from these defences.
Mate in three
A simple problem where the key move provokes mutual obstruction between the black pieces. There is a bonus feature which you may well spot when you are solving the problem.
Mate in three
This problem has a strong puzzle flavour. You’ll probably soon be home and dry once you spot which black piece needs to be obstructed.
Any queries or constructive comments can be addressed to the author at david.friedgood@gmail.com.
Copyright in this article David Friedgood 2012/ChessBase
The
British Chess Problem Society (BCPS), founded in 1918, is the world's
oldest chess problem society. It exists to promote the knowledge and enjoyment
of chess compositions, and membership is open to chess enthusiasts in all countries.
The Society produces two bi-monthly magazines, The Problemist and The Problemist Supplement (the latter catering for beginners), which are issued to all members. Composers from all over the world send their problems and studies to compete in the tourneys run by the society.
The BCPS also organises the annual British Chess Solving Championship, and selects the Great Britain squad for the World Chess Solving Championship. The Society holds an annual residential weekend, with a full programme of solving and composing tourneys and lectures; this event attracts an international participation. Members are also entitled to use the resources of the BCPS library, and the Society book service, which can provide new and second-hand publications.
