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March 1998's Go Answer of the Month

Dia 1 - Black to play.

I was shown this problem at Oxford this year. It isn't as obvious as it at first seems.

Dia 1

How does Black answer this? Kos and sekis are a failure. What if Black tenukis?

First the replies which don't work...

Dia 2 - The 'obvious' 3-2 point.

Dia 2

After White sacrifices 3, which Black has to capture or Black loses his second eye. Playing 6 at 3 is self-atari, therefore Black has to fight the ko in the corner.

Dia 3 - So lets try the 3-3 point.

Dia 3

Another ko. Black cannot capture with the corner point as White just links 3 and 5 out.
Playing 4' at 5 gets Black 5' at 4, and it's still a ko.

Dia 4 - How about the other 3-2 point?

Dia 4

Black cannot capture 3 - White snaps back. Therefore we end up with a ko at 5 and the 1-1 point.

Dia 5 - Getting desperate!

Dia 5

White 3 is a double atari. Black is well and truly dead.

Dia 6 - Which leaves the other 1-2 point.

Dia 6

Surprise, surprise. This works.

Dia 7 - What about a Black tenuki then?

Dia 7

The tenuki appears to be no worse for Black than most of his direct replies. It turns into a ko.

Dia 8 - For your further study ...

Tim Hunt proposed the following extension to the original question. I do not plan to answer this.

Dia 8

How much is first move in the corner here worth?
(Or - how much better is the best White play than a "normal" White play?)

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