Beginner Exercise 28 / Solution

Sub-page of BeginnerExercise28
Ko for life - Black captures first  

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

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

Black fears ko - and dies for it  

To avoid the ko is impossible - here, White falsifies an eye so Black is left a cyclops.

leoger: Doesn't B4 at W5 here secure life and avoid the ko?

unkx80: Self atari, already answered below.

why not this?  

mookie?:If white plays at W1, black can connect at B2, then if white plays at a b or c, black can play at either a or b. Black only needs to make one eye because he connected to the eye of the other black group, and he will secure that eye by playing at either a or b. I am a beginner, am i missing something?

Dieter: Good idea! But there is a catch: try both options again and count liberties.

mookie?: Oh, I see. If white plays at a or b and black takes the other, then white simply plays at d and captures that whole group. Thanks!

Resistance, variation - 5 at 3  

Again avoiding the ko yields only death for Black.

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.

Failure 1  

The throw-in here doesn't work - the marked point will become a real eye for the corner group, so the two disconnected black groups will have one real eye each and a shared eye - and thus live.

Failure 2  

A similar result occurs if White approaches from the side.

Black almost lives =)  

Black Lives  

W3 is a mistake

Beginner Exercise 28 / Solution last edited by on January 15, 2012 - 19:37
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