Shape Problem 6 / Discussion

Sub-page of ShapeProblem6
[Diagram]

White to make shape (i)

Charles So I see this ladder ...



[Diagram]

White to make shape (ii)

... and if the ladder (actually, either one of parallel ladders) is good for White, White might have no problems here. The net might be a strange ko.[1]



[Diagram]

White to make shape (iii)

Backtrack to here, which is the first chance for White to vary.

[Diagram]

White to make shape (iv)

W1 looks good because the capture now for Black causes shortage of liberties. But if Black answers by extending from black+circle, it's a serious ko.


[Diagram]

Attempt

unkx80: Takes some reading to see this. B6 is neccessary to prevent a. After this, White can play elsewhere.

Charles Yes, I thought of W1 just after I went out shopping.

HolIgor: When I set this problem I has this solution in mind. The discussion that followed was interesting, so I will wait for the final words before making the solution page.

Bill: I think that on an empty board (except for the ladder breaker) I would like this variation, keeping sente. I also think that the choice among this variation, the first net variation, and the second net variation depends upon the rest of the board.


HolIgor: Wow, quite a heavyweight discussion.

I played the variation leading to ko and consider it wrong. Yet, for the benefit of beginners I will explain what I wanted to achieve.

[Diagram]

What White had in mind

After clearing up the captured stones

[Diagram]

Shortage of liberties

Black cannot connect because of the shortage of liberties and has to play B1. White capture and black takes firm grip of two white stones.

[Diagram]

The result

The final white's shape is excellent. It is thick, the eyes are almost there and white kept sente.


HolIgor: What happened in the game was, however a ko

[Diagram]

What white had in mind

Black extended with B2 and after W3 captured with B4. White had to play elsewhere and black filled the ko producing the following position

[Diagram]

The result in the actual game

This was not too bad for White either because there is a great piece of advice that ugly shapes have to be sacrificed; and the shape of the white+circle stones is ugly.


[1]

Charles Actually, I think we're not yet done with this very interesting question: see Shape Problem 6/Net variation.


[2]

[Diagram]

Another net

Bill: As long as we're willing to sacrifice the ugly stones, this doesn't look so bad.

Charles Indeed. But gote.


This is a copy of the living page "Shape Problem 6 / Discussion" at Sensei's Library.
(OC) 2009 the Authors, published under the OpenContent License V1.0.
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