Portal:Chess/Selected article/Introduction/Zugzwang
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Zugzwang (German for "compulsion to move", pronounced [ˈtsuːktsvaŋ]) is a term originally used in chess which also applies to various other games. The concept finds its formal definition in combinatorial game theory. It describes a situation where one player is put at a disadvantage because he has to make a move - the player would like to pass and make no move. The fact that the player must make a move means that his position will be significantly weaker than the hypothetical one in which it is his opponent's turn to move. In game theory, it specifically means that it directly changes the outcome of the game from a win to a loss. The term is used less precisely in games such as chess; e.g., the game theory definition is not necessarily used in chess. For instance, it may be defined loosely, as "a player to move cannot do anything without making an important concession". Zugzwang is a common technique to help the superior side win a game and sometimes it is necessary to make the win possible.
The term zugzwang is frequently used in chess. A player whose turn it is to move who has no move that does not worsen their position is said to be in zugzwang. Thus every move would make their position worse, and they would be better off if they could pass and not move. Sometimes different chess authors use the term zugzwang in different ways. In some literature a reciprocal zugzwang (see below) is called zugzwang and a one-sided zugzwang is called a squeeze.
