Atari (Go)
Atari ( Japanese. 当 た り ; in German about "hit" or "success") describes a position in the Japanese board game Go in which stones can be struck.
In the Go there is a group with (only) exactly one freedom in the Atari. In the picture on the right, all black groups are in the Atari, but no white ones. The points marked by circles are the last freedoms of the groups. As field C4 shows, it is entirely possible that several groups share a common ultimate freedom. This can be a maximum of four, as each field can have a maximum of four neighboring fields (there are three and two at the edge and corners).
A group without freedom cannot exist on the board according to the rules of the game. If a stone is placed that takes the last freedom of one or more opposing groups, this group must automatically be removed from the board. As a result, according to most Go rules, it is also forbidden to set a stone whose group would no longer have any freedom after setting, i.e. to make a so-called “suicide” move. In the variants in which suicide is allowed, the stone and the rest of the group must then be removed from the board. The stones count as prisoners of the opponent.
A special case occurs, however, when the stone placed not only takes away the last freedom of your own group, but also that of at least one of the opponents' groups. In this special case the stone can be placed and the opposing stones are caught. In our example, a white stone on J9 would not be suicide, but would hit three black stones. This means that your own group has at least one freedom and can exist (i.e. not both groups are taken off the board). The Kō rule is an exception .
A position can be saved if a move increases the number of freedoms. A group in which there is no such move or no such sequence of moves, so they are back in the Atari with each move, is called Oi-otoshi (“doomed”). However, the reverse conclusion cannot be drawn. So if there is a move with which the number of freedoms can be increased, then the group cannot be captured in the next move.
Groups in the Atari are not necessarily defeated by the opponent on the next move. What is to be assessed is the ability of the stones to escape and the consequences of this. If there is no move sequence that saves the trapped group anyway, the capture is usually a wasted move and the player will turn to other parts of the board ( tenuki ). The local point gain could simply be too low compared to other trains. If so, the situation would be revisited by the players at a later stage in the game. The advantages of direct hitting are, in turn, that a possibly weak surrounding group becomes strong with one stroke and any potential for the opponent (e.g. playing stair breakers) is extinguished. Conversely, trapped groups that remain on the board may later intervene in the action again, for example if the surrounding stones are weakened in the course of the game.