Beginner Exercise 14 / Solution

Sub-page of BeginnerExercise14
[Diagram]
White first, what happens?  

KarlKnechtel: In order to live, Black must either make two eyes out of the circled points, or one out of those and one at the squared point.

[Diagram]
Solution: White kills  

The placement of W1 prevents the first way right off the bat. W3 at B2 would mean no eye at the squared point, so Black must play there to have any hope. W3 threatens to falsify the eye at b, but Black cannot play there because of shortage of liberties.



Without W1, the play at b would be possible. Thus W1 is a dual-purpose move of sorts - well, it accomplishes two things, but both are oriented towards killing the black group, so I don't know if you'd count that. If Black captures the W1 stone with a, White goes ahead with W5 at b to falsify the eye.


Let's consider other options for White. If White tenukis, B1 at W1 would save the group, but I think B1 at B2 or b do as well. So maybe W1 at B2 or W3 can be made to work. First let's consider W1 at W3:

[Diagram]
Can White kill this way?  

W1 does not work, since B2 saves the black group (this is Black's only move!). Note that playing B4 to capture at a is wrong, since then W5 at B4 falsifies black's eye.



Now let's look at the other candidate move for White:

[Diagram]
White failure  

This one doesn't work either - a and b are miai for Black to live. Alternately, White a can be answered at c, removing a tiny bit of aji (after the a-b exchange, White could kill with three local moves in a row). Not worth the one-point sacrifice, probably. Not at my level of play anyway.


[Diagram]
Another possibility (4 at 1)  

Grech: What if White calls the tune like this?

[Diagram]
Black can live (5 at 1)  

Stefan: Black should answer differently. If he answers the atari at W3 at B4 here, White may capture one stone in ko, but the rest of the black forces survive if Black calmly makes the second eye at B6.

[Diagram]
White 1 is wrong, but...  

unkx80: W1 is incorrect, but after that the placement at W3 still can create a ko.

[Diagram]
Alternative Solution?  

letsgo4it?: I believe this also works. Even if Black plays elsewhere after 1, White can easily finish it off.

fractic: This sequence doesn't work. Black will live by playing at a next, it creates two real eyes at the circle.

[Diagram]
Alternative Solution  

Fragnix?: I believe this also works. The key is to take the vital point 3. Black can't answer anywhere else but 2. However, this solution is suboptimal to the main solution.

[Diagram]
 

This becomes a ko fight, which is a failure for W since there exists a line which kills outright. The W1 B2 exchange is bad for W, as the only thing it seems to accomplish is setting up a ko fight around W1.



Beginner Exercise 14 / Solution last edited by 96.47.186.242 on June 6, 2011 - 21:07
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