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Bent four in the corner
Path: LifeAndDeath · Prev: CarpenterSSquare · Next: TwistedFourInTheCorner
Difficulty: Advanced
Keywords: Life & Death, Rules
Bent four in the corner is an expression referring to two things.
1. Fewer than two outside liberties
If the defending shape has fewer than two liberties on the outside, Black can prevent unconditional life for White's group and make a ko by playing at a.
White responds with an atari at White can't play oshitsubushi at a, because of shortage of liberties; and the fate of the group is decided by a ko fight. Finishing the ko 2. At least two outside liberties
If White has an extra liberty on the outside, however, she can play the atari at
So, if 3. Making bent four in the cornerThe position becomes more complicated when the eye shape is almost filled in the following ways.
White can play at neither a nor b because having her eyespace almost filled with straight three means death. Therefore Black can fill the marked outside liberties at any time, before playing a. As we now know this starts a ko. We now refer to the page bent four in the corner is dead to explain why this is dead as a rule.
Black cannot play either at a or b, because White will play c to almost fill the eye space with bent three, which kills. Therefore White can fill the marked outside liberties at any time, before playing c then a or b. Again, as we now know this starts a ko and we refer to the page bent four in the corner is dead to explain why this is dead as a rule. [1] Finishing the ko
With a single outside liberty, Black finishes the ko by almost filling the eyespace with a bent three. Playing 1 at a reignites the ko and gives White a second chance.
With no outside liberties, Black can finish the ko by capturing all the stones. Playing Avoiding The Bent Four
Some exercises involving bent four in the corner:Authors
Path: LifeAndDeath · Prev: CarpenterSSquare · Next: TwistedFourInTheCorner This is a copy of the living page "Bent four in the corner" at Sensei's Library. ![]() |