Endgame Problem 9 / Solution

Sub-page of EndgameProblem9

The informal analysis

[Diagram]

Solution

W1 is the solution, not a.

[Diagram]

Solution

What is so painful for Black is that W5 is practically a sente move during the endgame phase. After B6, then White can tenuki, so White has reduced Black's territory in sente.

[Diagram]

Variation

B2 does not work either. Black loses even more this way.

[Diagram]

Failure

W1 is considered a failure in this problem. After B4, if White saves the two stones at a, then it is gote. Nothing more than an itch for Black.



The more formal analysis

[Diagram]

Almost sente

Bill: W1 - W3 is fairly large, about 8.7 points.

[Diagram]

Large gote

W10 connects at black+circle.

B1 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 B5 - W6 is sente, and even later B9 - W10 is sente.

The count in this end position is -1 for the captured stone. White at B9 would forestall 2 points and then create a ko to capture first in sente. So B9 is a 2 1/3 sente. White at B5 would forestall 3 points (and no more if Black is komaster), so B5 is a 3 point sente

[Diagram]

Large gote

Here the count is 8


%
%

Game tree

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

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