False Eye
A false eye is something which possibly looks like an eye, but really isn't one.
Usually false eyes on the edge suffer from at least one opposing stone diagonally to them, and those in the center from at at least two such stones. See also recognizing an eye.
The black group has a real eye and a false eye. The false eye is the one at a.
Notice that the marked black stone has an incomplete connection with the rest of the group: a suffers from both marked white stones.
Also, if White fills up the exterior liberties at b and c, the two black stones are in atari. If Black connects them at a, the "eye" obviously disappears. Just the same if Black allows their capture.
Thus, a false eye is not an eye.
Here's another false eye which you will encounter frequently in games. Even if the marked stone gets captured, there is no real eye here for Black.
The stone is a throw-in, a technique commonly used to destroy eyes.
Elroch: The discussion page presents a different and possibly controversial viewpoint, on which discussion is extremely welcome.
See also:
- Eyes collection
- Eye
- Half Eye
- Two Eye Formation
- Two-Headed Dragon
- Instant Eye Tester
- Life and Death
- false eye life sometimes even groups with only false eyes are alive