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 |
If White plays first, White lives unconditionally, and kills the Black stones as well.
If Black plays first, Black kills unconditionally.
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.
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).
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.
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.
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
Note: Below is advanced material.