Life and Death - Status of A Group

Status of A Group

The concept of 'status' is discussed in Life and Death by James Davies. Groups of stones are divided into those that are alive, dead or unsettled. Here alive, for example, is an unconditional judgement made, that with best play from both players, the group can survive to the end of the game. That assumes the opponent starts: the alive status means that, whatever the attack made, there is an adequate defensive answer.

The unsettled status is therefore most worthy of attention. By playing first, the attacking player can kill such a group. By playing first, the defending player can save such a group. There is an enormous range of formations that are unsettled.

A group can be considered "alive", "dead", or "unsettled" based on whether two eyes can be made regardless of how the opponent plays. Naturally, one space is insufficient. Two adjacent spaces are insufficient to make two eyes as well, since putting a stone in will create one eye only. The opponent can simply fill in one of the two spots, threatening to fill in the other, forcing the player to capture that one by playing in the second one. Then, the opponent simply plays there again, killing the group. Usually this will not be done during the game, but at the end, during calculation, the group will be labeled "dead" and removed as prisoners. The only way to actually remove a group from the board is to fill its "eye space" with all but one, forcing it to capture the filling-in group by putting a stone in the last space. If the created group is not alive, then continuing this process will eventually kill the entire group.