... 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]
looks good because the capture now for Black causes shortage of liberties. But if Black answers by extending from
, it's a serious ko.
unkx80: Takes some reading to see this. is neccessary to prevent a. After this, White can play elsewhere.
Charles Yes, I thought of 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.
Black cannot connect because of the shortage of liberties and has to play . White capture and black takes firm grip of two white stones.
HolIgor: What happened in the game was, however a ko
Black extended with and after
captured with
. White had to play elsewhere and black filled the ko producing the following position
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 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]