Beginner Exercise 28 / Solution

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Solution

[Diagram]

Ko for life - Black captures first

The sequence from W1 to B4 yields a ko for life. Black cannot connect at a without removing the white stones because of shortage of liberties.

Note that the order of W1 and W3 can be interchanged.

[Diagram]

Black fears ko - and dies for it

To avoid the ko is impossible - here, White falsifies an eye so Black is left a cyclops. (B4 at W5 is a self-atari.)

[Diagram]

Variation (W5 at W3)

Again avoiding the ko yields only death for Black.


Failures

[Diagram]

Failure 1

The throw-in here doesn't work - the marked point will become a real eye.

[Diagram]

Failure 2

A similar result occurs if White approaches from the side.

[Diagram]

Failure 3

W3 is a mistake.


[Diagram]

Almost miai

JoelR: This is one of a class of problems where it looks like the defender has a sure thing because of a set of miai plays, but the task is to find the one combination that makes the pairings false. In this case, Black wants an eye at circle, and can get it if he holds either a or b, and either c or d. But wait, if White takes both b and d.... I don't see this line of reasoning presented as often as it occurs to me. A good example where it is on the page is six die but eight live.



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