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Two Eyes
Path: LifeAndDeath · Prev: Eyes · Next: EyeSpace Path: EyesCollection · Prev: Eye · Next: FalseEye
Difficulty: Beginner
Keywords: Life & Death
To be safe from capture, a group of stones must have two eyes (or be able to make them in response to any threat). This is the primary way to make groups alive (the other, less desirable way is seki). The basic rules of go state that when a group's last liberty is removed, the group is captured (removed from the board). It follows that, if a group has at least two liberties which cannot be removed, then the group cannot be killed and is alive. All subtleties aside, such an unremovable liberty is what we call an eye.
Look at the circled points. A White stone placed on any of them would be disconnected from her own stones and would have no liberties. Both Black chains would still have the other circled point as a liberty. Such a White move would thus be illegal. Neither of the two circled points can be occupied without the other. In conclusion, the circled points are two unremovable liberties of the Black group, or two eyes and it is impossible to remove the Black group from the board.
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Path: LifeAndDeath · Prev: Eyes · Next: EyeSpace Path: EyesCollection · Prev: Eye · Next: FalseEye This is a copy of the living page "Two Eyes" at Sensei's Library. ![]() |