Beginner Exercise 45 / Solution

Sub-page of BeginnerExercise45

Table of contents Table of diagrams
Solution
Solution
Failure: seki
Failure: ko
Solution
Solution
Solution
Failure: seki
Sacrifice option 1
Sacrifice option 1
Sacrifice option 2 (W2 plays elsewhere)
Sacrifice option 2

Status

If White plays first, White lives unconditionally, and kills the Black stones as well.
If Black plays first, Black kills unconditionally.

White first

[Diagram]
Solution  

The key move for White is to descend with W1.

[Diagram]
Solution  

If B2 blocks here, then W3 allows White independent life. Note that Black cannot approach at a.

If B2 at W3, then W3 at B2 captures the corner Black stones just as well.

[Diagram]
Failure: seki  

The hane at W1 would be an instinctive move, but in this problem it is a mistake. Now B2 can make a throw-in, and after B4 White cannot approach at either a or b. The result is seki (with a sending-two-returning-one option for White at b).

[Diagram]
Failure: ko  

Starting a ko with W3 is a risky preposition - it puts the life of the entire White group at stake. In life-and-death problems, by convention ko for life is always treated as inferior to unconditional life - and rightly so.


Black first

[Diagram]
Solution  

The only way to kill is to descend with B1.

Unlike most other problems, the proverb the opponent's vital point is my vital point does not apply in this problem.

[Diagram]
Solution  

White just does not have the liberties needed anymore.

[Diagram]
Solution  

In this variation, White is still dead. White cannot play at a because of a shortage of liberties.

[Diagram]
Failure: seki  

Although White at B1 is the key for making unconditional life, Black playing at B1 here only results in a seki after W2 and W4.

This nice seki features

  • an one-sided dame for Black (at W2),
  • a sending-two-returning-one option for Black (at a), and
  • two sacrifice options for Black, both of them leading to seki again (to be elaborated in the diagrams below).


Note: Below is advanced material.

[Diagram]
Sacrifice option 1  

This is the first sacrifice option.

[Diagram]
Sacrifice option 1  

The result is again a seki.

[Diagram]
Sacrifice option 2 (W2 plays elsewhere)  

Black can also choose to fill up both 1-2 points.

[Diagram]
Sacrifice option 2  

This leads to the same seki position as the first sacrifice option.



Beginner Exercise 45 / Solution last edited by Unkx80 on May 19, 2009 - 19:17
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