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In Go World 84, on page 59, there are a series of "Throw-in tesuji" problems.
Problem 5 seems to me more interesting if one of the failure answers is investigated.
I paraphrase Go World: "After the exchange of Black 1 for White 2, Black 3 is an unimaginative move. White can connect with 4, so the six black stones will be captured."
This month's problem is to investigate this statement, to either kill the six black stones or to demonstrate that they cannot be killed.
After the sequence in Dia 1 it is Black's turn to play, and since the 'book' suggests that Black's cause is hopeless let's give Black the benefit of the next move. 5 here seems plausible: it removes a liberty from white and reduces the space available in the corner.
After 5, White has to play at one of the three marked points to protect the cutting point. With any other play, Black plays at the middle and removes the white group on the next move. We can consider this to be a Black success.
Lastly note that I am endeavouring to demonstrate that Black can kill White. To that end, this and the following diagrams will have White 2 from Dia 1 at A here. This reduces Black's liberties by one and makes it harder for him to succeed.
If White 6 connects, then both groups have 5 liberties, so Black has to play a white liberty. 7 seems as good as any.
I've been through most White 8's and this seems the strongest of them all.
Other plays by White for 10' onwards are easy to refute.
The other two possible moves for White 6 are easily countered.
I conclude that Black can kill White.
An Ishi format file of these investigations is available.
Problem of the month
British Go Association
Last updated 2004-08-10
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