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Chessville
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What is a Chess Problem? Peter's Problem World with FIDE Master of Chess Composition Peter Wong In this column Peter provides help with words or phrases that have special meaning in the field of chess composition. These words and terms appear in the form of a pop-up box containing a short explanation and possibly a link to an explanatory page or example elsewhere. Click on the words "pop-up box" in the last sentence to try it out!
How exactly are themes artistic? It varies, but important factors include subtlety, elegance, economy, paradox, and unity of play. The latter concept of unity is especially noteworthy; most good problems have multiple variations that are related to each other in some way, to create a harmonious impression. Chess problems come in a variety of genres, the most common of which is the directmate. In this type of problem, White plays first and forces mate in the specified number of moves, against any Black defence. Only one of White’s first moves is able to achieve this, and the solver’s task is to discover this unique move, called the key. (Key-moves are signified by ‘!’.) If another move, unintended by the composer, solves the problem too, that alternative move is called a cook, and the problem becomes unsound. Such defective problems, however, are rarely seen nowadays (especially in short directmates) because of the practice of computer-testing, which ensures that cooks are eliminated.
Such a tactic, in which White stops a check by interposition, and gives check as well with the same move, is known as a cross-check, and its recurring use is the theme of this problem. Various conventions apply to key-moves in directmates, and knowing them will assist you when solving this type of problem. The desired feature of subtlety means that keys are very unlikely to be checks. Keys that capture a piece are almost unheard of, for the same reason, though the capture of a pawn is acceptable. In contrast to obviously aggressive keys that are frowned upon, keys that apparently weaken White or strengthen Black are viewed as good in the artistic sense. Though not all directmates are successful in incorporating them, you should keep in mind the possibility of such paradoxical keys. A perfect illustration is 1, which has an excellent key because it exposes the white king to numerous checks. Another major consideration when analysing a problem is whether the key creates a threat or sets up a block position. The former is already exemplified by 1, a threat-problem. In a block-problem, the key carries no threat but is a waiting move that puts Black in zugzwang. In such a position, every possible move by Black entails a weakness, which is exploitable by White because Black is compelled to move.
Looking at the problems in this article, you may be struck by how the positions seem “artificial” and far removed from an actual game of chess. That only highlights how problem compositions are a field distinct from the competitive game and also from game-position problem exercises. Chess compositions are constructed in accordance with their own principles. A particularly important one of such principles is economy of force, which holds that for any given idea shown in a problem, the number of pieces used should be minimized, and that every piece should serve to bring about that idea or to ensure soundness. That the resulting problem positions do not resemble game situations is regarded as irrelevant. Nevertheless, another convention of problems links them directly to the game. Problem positions are required to be legal, i.e. they could have arisen from the opening array, however unlikely the players’ moves may have been in reaching these positions.
In three-movers, White starts with the customary key, and after the black defences White proceeds with the second move continuations. Usually, for each defence there is only one correct White continuation, which – whether by making its own threat or by zugzwang – leads to mate on the third move.
Have a go at solving 6; its solution will be provided next month: 6.
Lev Loshinsky
Mate in 2
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