4-4 point one-space low pincer invasion, block

  Difficulty: Advanced   Keywords: Opening, Joseki
[Diagram]
Basic joseki  

Black blocks at B4 if he has a stone near black+circle (however, see also: 44PointOneSpaceLowPincerNoSupportStone?). Up to B8 we see a typical joseki: Black makes a wall facing the left side, while White gets eyespace and a small amount of territory in the corner. If the marked stone is not present, this variation is bad for Black. White then plays in this region herself, and thus effectively reduces the influence of the black wall. The connection B6-B8-B2 is rather thin, but for White to attack it at once would do more harm than good.


[Diagram]
Extension  

With the combination of W1 and W3, White aims at the cut at W5. Black most usually defends this cut indirectly - either by strengthening his position on the upper side, or by closing off the left side like he does here. If White cuts with W5 (often she will wait a while before doing so), he accepts the challenge with B6 (pushing White along the fourth line with B7 is not good[1]). The moves to White 11 (at a) are one possible continuation.

[Diagram]
The old joseki  

The old joseki, which is still played, was for Black to defend the cut directly with B1. The disadvantage of this move is that it leaves the large move of W2 as aji. If Black blocks with B3 at W8, White has a lot of aji here which might be used to invade Black's left-side moyo. But if Black draws back to B3 instead, White can make a rather large reduction of his territory in sente. Instead of W2, white could also play at W8.


unkx80: This needs clarification: is the W4 variation below an old joseki or a situational joseki? Because the result is supposedly better for Black.

[Diagram]
Slightly out of style  

W4 is another joseki move, but not played as often as the previous two. The sequence to W10 is forced, after that Black can choose to build thickness with a or fight immediately with b. a is most common.

Note that B7 cuts the side Black doesn't want. Having B7 to cut at B9 is the wrong place to cut, see tewari example 7 for an explanation.

The Suzuki-Kitani Small Joseki Dictionary says that this joseki is good for Black.

[Diagram]
Influence (6 connects)  

The B5 and W6 exchange is optional and only made in about half of pro games.

unkx80: Is there a particular reason why this exchange is not made?

After B1, this sequence is to be expected. White has sente, but Black's influence is large. However, note that there is a White invasion at triangle that is hard to deal with. For example:

[Diagram]
Disaster for Black  
[Diagram]
Disaster for Black 2 (4 at 1)  

In this line Black dies and the game is over. Instead the best Black can hope for (if they play B2 on the outside) is ko:

[Diagram]
Picnic ko for White  

If Black decides to fight:

[Diagram]
A favorable fight  

If Black plays B1, he should not forget the important exchange of B3 for W4. After B7, White is floating in the center, while Black is both strong and in a position to make territory on both sides. If White does not answer in the corner, Black can get a ko.

[Diagram]
Not afraid  

Black should not be afraid of this W4. Black can maintain his connection to the outside world, while White still has to come back in the corner.


Tirno?: Kogo's Joseki dictionary shows the following sequence and says White is better. I imagine Black should have additional support to play this way. Black b instead of 7 may also be possible.

[Diagram]
Good for white?  

The Black stones on the left make inefficient shape. The circled stone on the star point ends up making inferior shape and looking submissive; White retains significant aji below in addition to the endgame at a. Black's stones on top are low. Although White's center is floating and can later be attacked, the stones are light, flexible, and efficient.


Author: AndreEngels

See also thickness example 1, thickness example 5.


[1] One should say, rather, that it might not be good. It is certainly played by strong players. Charles


4-4 point one-space low pincer invasion, block last edited by sligocki on March 1, 2016 - 03:34
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