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Defending an enclosure
Path: EnclosureTechniques   · Prev: InvadingAnEnclosure   · Next: Probe
    Keywords: Opening

[Diagram]
The attack

Black has set up a fairly decent position, and White approaches with W1. The play at a feels like the right response, if passive. In the game, I played b, anxious about seizing this big point (my opponent immediately played in between b and my enclosure, aggravating me to no end). So. Is a the proper response? Is there anything better?

-- Scartol



Alex Weldon: My rank's actually only about the same as yours (currently fluctuating between 13k*-15k* on IGS) but it seems to me that your shimari is stronger than the two white stones already present and much stronger than the white stone he played between the shimari and the extension. Surely if he plays there you can arrange a powerful splitting attack against the two groups? If, on the other hand, he ignores your extension and slides in at a, or one below, you get good thickness from your shimari and use it to build a big moyo on the bottom side.

Anyway, a looks overconcentrated to me. I would have played the extension like you did, or maybe one further to the left, but like I said, I'm a weak player, so don't take me too seriously. I'm just trying to get some discussion started, to hopefully entice one of the stronger players to say something so deep and meaningful that we'll both instantly become two stones stronger upon reading it. :)


HolIgor: Why did you play this kind of high shimari? Perhaps, to become stronger in the center. So, the lower side should be the direction of your play. The move at b is a little bit too close, perhaps since it is not at the optimal position with respect to the future kakari of the bottom left corner. The move at a has the advantage that it takes away a good point from the white group at the right side. It is a good move, not immediately though.

As for the opponent playing between your shimari and the extension, that kind of play is very scattered and you should be able to get good result attacking that stone. A fight this early is in Black's favour.


Alex Weldon: Wow. I'm pleased. From what Holigor said, I actually sort of gave the right answer. One question, though, for Holigor, or whoever else... I was right to think that b is too close an extension. I said one to the left, but is that still too close? How far should one extend from a small high shimari like this?


adamzero The three moves that I would consider would be the side star, the point below it, and the point one to the left of the point below the side star.

I would decide which one to play depending on the following: If it seemed like other areas of the board were hot enough to prevent my opponent from playing on the bottom side soon, I would play the high extension, hoping to be able to make a kakari against White's star and then complete my framework when she responded. If White's corner were stronger, I would play the low extension, hoping later to play a one-space jump above it to form a box moyo, or simply the tent point in between my shimari and extension if White had developed a strong center.

The farthest extension I would find the most questionable, unless White's corner were weak and I had some more strength over the white group on the right side which would make it more unreasonable for her to invade the bottom side. That said, I wouldn't even consider a unless by doing so I would be far more seriously threatening White's side group than I am in the present case, and I would dismiss b as too short unless White had played a four-space extension from his corner -- which would be a very unusual extension.

Yilun Yang's lectures say a five-space extension is good for development, a two-space for stability, and three and four are generally inferior half-measures, though I see so many three-space extensions in pro games that, in my arrogance, I doubt that much of his wisdom. So that is how I would think through this position. Hope it helps.


[Diagram]
Dual-purpose move

Bill: Although it is a narrow extension, I think that B1 is quite playable. The point is not so much that it protects the corner -- simply protecting the corner is too small at this point -- as that it attacks the white group on the side, which is not quite settled.
White threatens to play at a, reducing Black's corner while stabilizing the White group. If White does not respond to B1, Black b knocks White's socks off.

Bob McGuigan: I agree with Bill. The white knight's move on the right side is too narrow. It does peep in at the weak side of Black's high enclosure but it doesn't help much in giving White a base on the right side. Consequently the White stones are heavy and a good target for attack.

If Black wants to play on the lower side the extension should be to the star point or the point below the star point. b in the first diagram is too close to the corner enclosure, i.e. it's inefficient. If White invaded into such a narrow space, with no support to the left it would only create a target for attack. Such an invasion is annoying if you don't have confidence in your attacking skills but it's actually something to be happy about in this case.


How does white make anything out of playing at a in the last diagram?

Bill: He makes a base for his weak group. It is now hard for Black to mount an effective attack against it. At the same time he reduces Black's corner. To evaluate the play you have to compare the position after it with the one after B1.



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