Beginner Exercise 156 / Solution

Sub-page of BeginnerExercise156
[Diagram]
Black to win the race  

Black wins with B1, a, or b. If Black a or b, White has a ko threat at c. With B1, White has a ko threat at b but c is not sente for White. Thus, Black may exchange c for d anytime (= 1 point sente).

So, I conclude B1 is best.

togo: And even better: If I see this correctly, White's ko threat at b only kills, if there is a white stone to run to (Although unanswered it weakens Black's stones considerably.).

xela: Also, a and b are different, in that for a, white's ko threat is a threat to capture the corner, whereas for b, white can only threaten seki. See the next two diagrams.

[Diagram]
Wrong answer 1: big ko threat  

If black ignores W2, then W4 will capture the black stones

[Diagram]
Wrong answer 2: smaller ko threat  

If black ignores W2, then W4 is seki.



Beginner Exercise 156 / Solution last edited by xela on October 23, 2022 - 06:33
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