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Eye
Path: EyesCollection · Prev: · Next: TwoEyes
Difficulty: Beginner
Keywords: Life & Death, Go term
Eyes are a central concept in Go, since two eyes guarantee the life of a group. And one eye can mean a great advantage in a semeai (close battle). Beware of a false eye that may look like an eye. In general, what Go players call an eye is an empty space surrounded by stones of one colour.
There is much discussion on the definition of what is an eye and what is not. The general eye definition is non-mathematical. There are also discussions of technical algorithmic definitions meant mainly for mathematicians and computer programmers, where absolute precision is needed. The Eyes Collection gathers links to many pages related to eyes at Sensei's Library. Grauniad: Why do all the examples of eyes on this and related pages contain a single point? Can't an eye contain more than one point? Won't single-point examples of eyes mislead readers? Stefan: An eye can indeed contain more than one point, as no doubt you know. Everybody figures that out in due time though, and I do believe there is more room for confusion of beginners if we include examples with more than one point. Dieter: We could do it, dividing this page into several sections. Velobici: Providing diagrams of a single eye with two spaces right next to the diagrams of a single eye with one space should not be confusing. It will clarify the matter for the beginner that two space is not two eyes unless the spaces are disconnected from each other. TJ: Something I point out to beginners, which seems often taken for granted as known, about forming eyes. If a group has more territory, it is more likely to be able to live if invaded. Whether it can live or not depends on shape. If the shape is seven points of territory or more, it cannot have its eye space compromised with correct defense, and can make two eyes.
Less than seven points, it depends on shape of the territory surrounded. So, a good starting point for beginners is to learn the status of the territory shapes between three and six. That's not such a huge task, and makes all that life and death stuff you keep hearing is so important a lot more comprehensible; not to mention stopping you from considering attacks that just won't work and freeing you to look elsewhere, and helping you stop wasting time with over cautious defense of perfectly safe groups in your games. On SL, check out Eye Space to learn all about these important shapes. Further ramifications directly deduced from this once the shapes between 3 and 6 are understood: Problems of Life and Death, both as exercise and within games, boils succinctly down to: Can a group can be cut off, and the territory it holds reduced to less than seven points of a shape which can be killed (death)/can such an occurance be avoided, or made to depend on the outcome of a Ko which will give the group life if won or give the player compensation for the killed group if lost (life). Capturing races are just a form of the same thing in which two opposing groups are trying to live/kill each other at the same time. Is this a good concise way of talking about what eyes are all about, and how to learn about them? If this is off topic, or is better stated elsewhere, or just too long winded, forgive me...I'm new here.:) TJ: Given the discussions can I re-edit this to read something like:
And then carry on with the rest pretty much as is? [1] See Nine point Eye - Possible Seki and Eight point Eye - Possible Ko Path: EyesCollection · Prev: · Next: TwoEyes This is a copy of the living page "Eye" at Sensei's Library. ![]() |