Endgame Problem 27 / Attempts

Sub-page of EndgameProblem27
Attempt 1 (6 at the position of the marked stone)  
Attempt 1 (continuation)  

White 13 and 15 are of course kept back as ko threats. Black's territory is reduced to 8 points, while white has captured a stone.

Black's failure  

B1 here instead of B8 is not good. White makes a seki. This is 6 points worse for black than the previous answer.

Andre Engels

Key point  

In this position, I think that W1 is the key point, instead of the atari at a. Next:

Key point (1): Seki  

If Black connects, White makes seki in sente, for a result of -4. (White has lost 2 stones, but Black will have to give up one later.)

Key point (1a): No Seki  

Oops! I had overlooked B4, which avoids both seki and ko. :-(

Key point (2)  

If Black takes the corner, White captures 4 stones in sente. The result is also -4. White has 14 points, but Black has 10.

Bill: Since I had overlooked Black's play on the 2-1 (B4 in the Key Point (1a) diagram), my original (supposed) solution was wrong. Let me try again.

Attempt 2  

(black+square was the last play before this diagram.) W7 connects at black+circle.

After Black fills at 2, W3 plays atari. Now B4 is tesuji, allowing B6. W7 - B8 is sente, which can be played later.

This position can be reached after W7 in Andre's original digram. B4 gains 2 points for Black, by comparison with the hane at 8.


Endgame Problem 27 / Attempts last edited by Bill on June 5, 2006 - 23:48
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