A ko as a ko threat

  Difficulty: Intermediate   Keywords: Ko
A ko for a ko  

In this game, there's a big ko going on at the bottom. Black plays B1 as a ko threat which in itself enlarges the ko at the right side.

Moves 187 to 191  

White takes the ko at W2 and resolves it at W4. Black does likewise with B3 and B5.

What's the value of this ko exchange? Let's evaluate the position if both had won the other ko:

Moves 187 to 191  

Compared to above diagram B3 makes 3 points, destroys 9 more and next a jump at a destroys 8 more in gote. Difference = 16

White makes 10, destroys 15 and also removes some aji (b is no longer sente). Difference = 25+.

Overall the exchange favors Black. Perhaps White saw the right side as potentially disconnected from the centre?

tapir: Shouldn't we determine status before counting territories? How does White live if she does not connect?

A ko as a ko threat last edited by tapir on May 7, 2018 - 22:00
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