Endgame Problem 9 / Solution

Solution  

is the solution, not a.

Solution  

What is so painful for Black is that is practically a sente move during the endgame phase. After , then White can tenuki, so White has reduced Black's territory in sente.

Variation  

does not work either. Black loses even more this way.

Failure  

is considered a failure in this problem. After , if White saves the two stones at a, then it is gote. Nothing more than an itch for Black.

The more formal analysis

Almost sente  

Bill: - is fairly large, about 8.7 points.

Large gote  

connects at .

is almost as large, about 8.4 (8.5 points when White is komaster). So White will often be able to play here with sente.

Later - is sente, and even later - is sente.

The count in this end position is -1 for the captured stone. White at would forestall 2 points and then create a ko to capture first in sente. So is a 2 1/3 sente. White at would forestall 3 points (and no more if Black is komaster), so is a 3 point sente

Large gote  

Here the count is 8

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Game tree

            3.5 (4.5)
          /   \
         8   -1 (3)
             / \
 (-2 -1/3) -1  -4
           / \
         -1  -3 -1/3