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Non-Local Move Versus a Local Move
  Difficulty: Beginner   Keywords: Tactics

Compare the following two situations (grossly oversimplified):

[Diagram]
Diag.: Black tries a ladder

and


[Diagram]
Diag.: Black tries a net

The way I see it (25-20 kyu), the second move is better because Black does not have to worry as much about the rest of the board.

The Ladder depends on the absence of white stones in the ladder-breaking-area (marked points - possibly I'm a few lines off here :-) ) while the Net nearly always works.



Correct. Kageyama writes:

  1. Check if you can capture a stone in geta.
  2. Check if you capture it in shicho.

I would like to comment on you diagram though. In the position on the diagram both moves are small, because white stone is not important (non-cutting stones). If you capture it you'll spend a move for 2 points, which is too small with so much empty space. As soon as the black group is alive, everything in this corner is yose.

I believe that one of the reasons low kyu players lose their games is because they make too many small moves. Get rid of the moves that capture a single not important stone and your strength will grow considerably.

To illustrate the same principle I would suggest a following diagram that is logical

[Diagram]
Diag.: Geta

Here, marked stone may run away splitting black in two groups. Each of them will have to live separately. Now Black 1 not only captures a stone, but also connects two groups and is likely to form an eye, which makes it a very good move.



Kageyama also says: if you can capture a stone firmly, don't capture it loosely.

Applied to your diagrams this means:

[Diagram]
Diag.: The net

The net leaves forcing moves at 'a' and 'b'.


[Diagram]
Diag.: The "ladder"

The ladder captures the stone more firmly, and actually it's no ladder at all, because after w2 black can play geta with 3.

(In fact, as a Geta, it leaves Kikashi's at a, b and c... ;-)) --AvatarDJFlux)

I'm not saying that this is the optimal move, I'd play the geta move at 1 myself, but one should always think about options and (gasp) think some moves ahead :o)

--ArnoHollosi



TheDullBlade:

[Diagram]
Diag.: Closing the net

This is the best closing technique I can see. Having this option is clearly preferable to having only a ladder aimed out into the wild blue yonder, but it still has to reach out a significant distance, and is also vulnerable to spoilers nearby. The early geta seems much more decisive and reliable.


[Diagram]
Diag.: Uh oh...

The above attack is dependent on the rather artificial isolated corner position. IMHO, a shape like this would be farther out and much less isolated. Furthermore, it also has the above-mentioned forcing points.

I've played around with this out in the middle, and it's messy. I'm not sure, but I think white can live, even without any help around.

It's seems to be a complicated situation. Can anyone point out a foolproof capture I missed?

AvatarDJFlux (3k): Yes, you spotted the right sequence in the first dia., except that W will never play it (especially W5...), because she hopefully can read that she has no way out. Instead she will keep the moves in reserve as possible Kodate's.
Of course the sequence works because you can drive W to the edge. So in your "Uh oh" dia. it does not work, if there are no edges or friendly stones in the right places nearby.

But: even considering that position in isolation on the Goban, W will have anyway a hard time trying to save her eyeless and shapeless string of stones, caught in the middle of two strong black positions!
In fact, as already mentioned by Arno, the whole discussion is a tad off mark: if the W stone is not a dangerous cutting stone, and sits all wilty and almost dead against a strong wall of B stones, W won't try to save it, as adding moves there just makes the resulting group heavier and weaker, a perfect attacking target, neither B will add moves to overkill it.
Unless of course the surrounding position changes dramatically in W's favour...

TheDullBlade: Ah, thanks. My point was that the "turn the ladder into a net" trick does not produce a neat, small widely-applicable net as the initial net does, but is dependent on odd circumstances. Usually a wall like that will exist to wall something off, in which case white can probably escape, either by reaching around or running out when black blocks the reach. In the process, she would destroy the eye point preserved by the initial net and threaten to surround and isolate black's wall.

This is my second encounter with Kageyama's "choose the firmer capture?" principle (the first at Geta). Both have lead to rather controversial advice. Is this preference for ladders really what he meant?

DJ: Not exactly: the idea is to capture the cutting stone(s) in a way to minimise the possibilities of threats of pulling it (them) out. IOW the firmer way is the one that gives the opponents the smallest number of Kikashi's (peeps, ladder breakers, etc.)
Please bear in mind that very often the combination of Geta and a LooseLadder (as in your first dia.) is the only way to accomplish the capture of cutting stone(s)...



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