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Big Question Mark Problem 1
  Difficulty: Advanced   Keywords: Life & Death

I'll write a question! This life problem has been bothering me ever since I found it over at the go server [ext] http://igs.joyjoy.net/English/lifedeath/es1.html

--FCS

[Diagram]
Diag.: Black to play and kill

Here's the initial situation, and the two moves that originally popped into my head were a and b.


[Diagram]
Diag.: Black plays 'a'

If Black plays at a, White captures at 2, already giving herself one eye. No matter how Black attacks, White will get another eye.


[Diagram]
Diag.: Black plays 'b'

If Black plays b, he puts the marked stone in atari. If White takes the bait and connects at 2, Black can play 3 and create a bulky five shape, killing White.


[Diagram]
Diag.: Black plays 'b'

But, if White ignores the trap, and plays at 2, then Black must capture White's stone at the marked space with 3 or die. White responds with 4 and the black group is trapped. Also, since the group is four in a row, White will be able to make eyespace.

   Hint: Don't stop here!
   You will do it.

Argh! I just found out the answer... Yes, there are four spaces in a row, but it's a bent four in the corner, which does strange things and in this case is dead.

(No, this is not a bent four in the corner, there are however some strange things that can happen here).


[Diagram]
Diag.: Black plays 'b'

Black reinforces at 5, and lets White take his stones with 6, only to play 7 and kill White.

White would like to play at the marked space (and would if 3 were White), but can't because 6 is in atari.

   No! This is a ko! Look again.

[Diagram]
Diag.: Ends in ko

OK, so White plays 8 and Black 9 leaving a ko. White would play a ko threat elsewhere so that she can take 9 back.


[Diagram]
Diag.: Where to play?

So, I'm left with this situation.



Solution to QuestionMarkProblem1



This is a copy of the living page "Big Question Mark Problem 1" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.