Eternal Life

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Keywords: Ko, Rules

Chinese: 长生 (cháng shēng)
Japanese: 長生 (chōsei)
Korean: 장생 (jangsaeng)

Eternal life is a type of cycle, where the position of the board repeats. Under some rule sets, a game in which such a situation occurs can become void (no result: neither player wins, but neither player loses). Several special rules, such as superko and the Ing Ko Rule, forbid the recurring sequence to occur.

However, eternal life is so rare in games that if one occurs, a Chinese Go text says that:

You should buy fish, vegetables, meat and wine
And have a good party to celebrate yourself

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Example

This is the situation to begin with. The white+square stone makes for a false eye. If White plays a next, the black corner group will die in a bulky five.

begins by sacrificing two stones, to prevent the formation of the bulky five. White must capture, otherwise black would take four stones and make life.

takes back two white stones...

White makes a throw in at to destroy the eye, returning the situation to that in the first diagram. The cycle repeats itself when at a sacrifices two stones again...

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Making seki

If Black has no outside liberties, White has the option of making seki:

Q: But suppose White needs to kill Black in order to win, and Black would never let go of his group?

A: Then eternal life occurs.

Note: Strictly speaking the position after White 1 in the Seki diagram is not seki, but a hyperactive position. However, when it is correct to make the play, it will almost always become seki.

There was some excitement about this thirty years ago when a variation of the kado joseki played in a title game Sakata - Yamabe could have led to chosei.

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