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In this 1928 game between Liu Changhua and Go Seigen, 112 and 
are a ko. What ko
threats does each player have?
Firstly we need to understand how big a ko this is.
In Dia 2, White 1 is elsewhere which Black ignores. White has no problem making two eyes and Black lives by connecting to his live stones at the bottom.
In Dia 3, Black 2 is a ko threat elsewhere which White ignores. Black now has no obvious eyes for his group and no obvious escape route. Thus this very large group is in mortal danger.
The ko was resolved in White's favour at move 152.
White 152
connects at
Dias 4 and 5 are identical except that in 5, black ko threats and their white answers are marked with red lines and white threats plus black answers with blue lines.
Note that White chose to play many threats in a row from 128 to 140 to build up his group in the lower central left.
The game is available as an ishi format file.
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British Go Association
Last updated 2004-10-16
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