Editing Rules of Go (section)

=== Seki ===
For defining this notion, it is useful to introduce some additional terminology:

;Terminology
* An ''eye'' is a connected group of one (or more) empty intersections entirely surrounded by a chain or chains of stones of one color. 
* A chain of one color is ''independently alive'' if it is (or can be made to be) adjacent to two eyes.

These definitions are given only loosely, since a number of complications arise when attempts are made to formalize the notion of life and death.

A group of stones of one color is said to be ''alive by seki'' (or ''in seki'') if it is not independently alive, yet cannot be captured by the opponent.
{{Go board 5x5
| w| w| b| b| b
| w| w| b| b| b
| w|  | w| b| r
| w| w| w| b| b
| w| w|dc| b| b|24}}

For example, in the diagram above, the black and white groups each have only one eye. Hence they are not independently alive. However, if either Black or White were to play at the circled point, the other side would then capture their group by playing in its eye. In this case both the black and white groups are alive by seki.

In the diagram above, the circled point is not surrounded by stones of a single color, and accordingly is not counted as territory for either side (irrespective of ruleset). In more complex cases, as here,<ref>Diagram taken from Robert Jasiek [http://home.snafu.de/jasiek/diffasts.html [s n a f u &#93;] {{in lang|de}}</ref>
{{Go board 5x5
| w| u| b|uc| b
| l| w| b| b| b
| b| b| w| w| w
|lc| b| w|  | w
| b| b| w| w|dr|24}}

a vacant point may be surrounded by a group of a single color which is in seki. According to Japanese and Korean rules, such a point is nonetheless treated as neutral territory for scoring purposes. Generally, the Japanese and Korean rules only count a vacant point as territory for one color if it is surrounded by a group or groups of that color that are independently alive.