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Ten Thousand Year Ko
Path: SecondCourseOnKo · Prev: ThreeStepKo · Next: Erratum8MannenkoDiscussion
Keywords: Ko, Rules
A ten thousand year ko, thousand year ko or mannenko is a ko that is not interesting for either Black or White to start early on. Players usually wait until very late[1] in the game to actually start it. One of the players also has the option of turning it into a seki.
A basic corner shape that leads to this mannenko is the long L group. The source of this ko is shown below[2]. Bill Spight: It is difficult for either player to start a ten thousand year ko because, when the ko is converted to a regular ko, the other player takes first.
It is easier for Black to convert this ko because Black has less at stake. [1] Dieter: I have difficulty understanding this. In the given position, if White wins the ko White makes 18 points whereas if Black wins it Black makes 10 points, compared to the "neutral state" which is seki. This means (in my humble opinion but I'm not at all sure) that White must maintain a set of bigger ko-threats than Black's. There are three phases in the game. The first one occurs when White's threats are big enough to fight the ko. The last one occurs when Black's threats have become too small to fight the ko. In between there is the phase where White's threats aren't big enough (<18 points) but Black's are (>10 points). Isn't this the phase where the ko will be started by Black ? Of course, it is a strong assumption that both sets of threats will decrease in value at the same rate.
Bill: You also need to factor in the fact that White can make a regular ko right away, while it takes Black 2 plays to do so.
[2] The above example was borrowed from an The paragraph which goes with the diagram follows:
Bill: Takahashi seems to have been the only person ever to avail himself of that option, leading to a rules crisis and a strange decision: Segoe won but Takahashi did not lose. Path: SecondCourseOnKo · Prev: ThreeStepKo · Next: Erratum8MannenkoDiscussion This is a copy of the living page "Ten Thousand Year Ko" at Sensei's Library. ![]() |