Beginner Exercise 258 / Attempts

Sub-page of BeginnerExercise258

First, I'll just show that White in the corner is dead if White does not play there.

If White ignores the corner group (1)  

In this game tree, White needs both a and b to live.

zinger: White is not dead. It is a ko. After B3, white plays b, and if he also gets to play a, his group is alive.

Warfreak2: Thanks, I missed that; I was thinking B1 was still there... oops.

If White ignores the corner group (2)  

White dead again.

zinger: Same as above: white plays a, and it is ko.

If White ignores the corner group (2)  

Dave: Careful, B3 and White is dead because she can't play at a. W2 at 3 is the right way to achieve ko here.

White's best move  

Here, W1 forms a bent four, which is usually a living shape. White is split into two chains, but each have three liberties. Any Black stone inside the bent four would have only two liberties, so it can be captured before Black can capture either White chain. Of course, White at either a would form two eyes, so White is alive.


At least, I think so. Anyone want to make sure I'm not missing something?

zinger: I believe black does have a way to kill white unconditionally, which is not yet shown on this page.

Bill: I agree. :-)

Warfreak2: OK, but is this the correct move for White? It is, after all, the one I suggested :) I wasn't sure it worked exactly like a bent four, as there is a cutting point.

If White ignores the corner group (5)  

Also, am I correct in thinking that B1 also kills White?

zinger: No. White answers at a. Now what does black do?

Warfreak2: Die, apparently. :/

clean kill  

AJP: Coming in from the outside against a J group type connection like this is a surprisingly severe attack.

messy kill  

Warfreak2: If B1 in your first diagram is Black's best move, then this is indeed a counter-example to Your Opponents Good Move Is Your Good Move: B2 after W1 is atari so White must play W3, B4 then kills.

Cryptoz?: W3 is self-atari. Black can kill at a.

Shaydwyrm: Black need not play at all after W3. If white plays an additional move, either a or B4 will kill.

Beginner Exercise 258 / Attempts last edited by Tas on May 27, 2008 - 11:06
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