Beginner Exercise 45 / Solution

Solution  

The key move for White is to descend with .

Solution  

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

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

Failure: seki  

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

Failure: ko  

Starting a ko with 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

Solution  

The only way to kill is to descend with .

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

Solution  

White just does not have the liberties needed anymore.

Solution  

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

Failure: seki  

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

This nice seki features

• an one-sided dame for Black (at ),
• 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.

Sacrifice option 1  

This is the first sacrifice option.

Sacrifice option 1  

The result is again a seki.

Sacrifice option 2 ( plays elsewhere)  

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

Sacrifice option 2  

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