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ThePracticalEndga...
EndGameTestOneSol...
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End Game Test One Solution 3
  Difficulty: Dan level   Keywords: Problem, EndGame

More analysis of "The Practical Endgame Test One".

Solution is White wins by 4 points - find it at EndGameTestOneSolution.


[Diagram]
Diag.: Can B keep the margin to 3?

When Arno posted this position, I became fascinated by the question can B force a better result than W+4? It took me a long time to think that I found the answer... --DaveSigaty



[Diagram]
Diag.: Variation 1

B plays 1 because otherwise the W play at 'b' is too damaging. W then goes back to 2, giving B the chance to capture at 3. If W now plays on the left, B plays 5 forcing 6. W can not ignore 5 because B 6 followed by descending to the edge is a very big play (even bigger than capturing the two black stones if W plays at 'd' instead of 6).

On the left side, B at 7 is the right way to play. When W cuts at 4 it is worth 2 points for B to ensure an eye on the left side. Otherwise he will have to play another stone on the right to prevent W's atari at 'c'.


[Diagram]
Diag.: W+3

B has 2 pts on the left and 10 pts on the right.
W has 4 pts at the bottom and 11 pts at the top.
W wins by 3 pts.

(note: don't forget to count the captured stones.)



[Diagram]
Diag.: Variation 2

W can try blocking at 4 knowing that she can win a ko fight. However, B does not need the ko to improve on the solution diagram...


[Diagram]
Diag.: Imperfect Reversion

Now note that if W captures at 'a' and connects, we have reverted to the solution diagram except that the marked W stone has been added inside W's territory. In addition each side has captured one stone near 'a' but they offset each other. Final result? W+3.



[Diagram]
Diag.: Variation 3

W plays 2 after reading out that she can't let B capture here. However, 3 is a big play with the follow-up at 5 as absolute sente. Play continues to 10 but W's winning margin has been reduced to a single point.



To summarize: if white plays the marked move in the first diagram black can force a 3 point loss, instead of the 4 point loss in the correct solution.



This is a copy of the living page "End Game Test One Solution 3" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.