Notchers

Notchers are recurring life-and-death patterns in which a group’s shape or eye space contains a distinctive notch or indentation. The group’s status depends on whether that notch can be exploited to reduce or remove its eyes, or whether the surrounding shape provides enough support for life. Recognizing notchers helps a player identify standard life-and-death patterns and locate their vital points.

Notchers describe a family of shapes, not a single move or tesuji. They are related to, but not synonymous with, nakade or with a generic eye. The exact result depends on the surrounding stones, available liberties, and the conditions at the edge or corner. A notched appearance by itself does not determine whether the group lives or dies.