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BQM 1
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  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]
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]
Black plays a

If Black plays at a, White captures at W2, already giving herself one eye. No matter how Black attacks, White will get another eye.


[Diagram]
Black plays b

If Black plays b, he puts WC in atari. If White takes the bait and connects at W2, Black can play B3 and create a bulky five shape, killing White.


[Diagram]
Black plays b

But, if White ignores the trap, and plays at W2, then Black must capture White's stone at the marked space with B3 or die. White responds with W4 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]
Black plays b

Black reinforces at B5, and lets White take his stones with W6, only to play B7 and kill White.

White would like to play at the marked space (and would if B3 were White), but can't because W6 is in atari.

   No! This is a ko! Look again.

[Diagram]
Ends in ko

OK, so White plays W8 and B9 leaving a ko. White would play a ko threat elsewhere so that she can take B9 back.


[Diagram]
Where to play?

So, I'm left with this situation.

(Reuven: Why wouldn't black play 3 one space above?)

Bill: Bad diagram, which I have corrected. There is a stone there.

Reuven, after you have read this, please delete our exchange. Thanks. :-)


BQM1 solution



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This is a copy of the living page "BQM 1" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.