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UnremovableKothreats
UnremovableThreats

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SecondCourseOnKo

Referenced by
KoThreat
Superko
MoonshineLife
BentFourInTheCorn...
AlmostAlmostFill
SekiWithEyesQuest...
KoThreatInSekiExa...

 

Unremovable Ko Threat
Path: SecondCourseOnKo   · Prev: GoResearchOnKo   · Next: Placid
    Keywords: Ko

An unremovable ko threat is a ko threat which cannot be removed without also executing the threat.

[Diagram]
Unremovable ko threat

Unremovable ko threats sometimes (always? all the ones I've seen...) occur in seki positions; here is an example. White has a ko threat here at a, which Black can never remove. Removing the ko-threat would mean Black playing at a himself, which of course leads to instant capture.



[Diagram]
One-sided unremovable ko threat

chewtonic: If Black answers White's move at a by playing at b (diagram above), White loses points. There is a class of positions which could be called 'one-sided unremovable ko threats' where one player loses nothing with their threat. See diagram on left.

Black can play any of the internal points as a threat that loses nothing (leaving a position similar to the first diagram if White answers), whereas White cannot threaten anything. If a bent four in the corner happens in another corner, Black would feel cheated, under Japanese rules. Note that if you reversed the colours in the bent four in the corner diagram, you would need to reverse the colours in this diagram too, to create a similar situation for White.



Path: SecondCourseOnKo   · Prev: GoResearchOnKo   · Next: Placid
This is a copy of the living page "Unremovable Ko Threat" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.