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

  Difficulty: Advanced   Keywords: Opening, Joseki
Traditional joseki  

After White's approach W1 and Black's pincer B2, Black blocks the invasion of W3 at B4 if he has a stone near black+circle. The idea is to form a wall plus an extension at an ideal distance, a typical construction of a moyo, while White gets corner territory and sente.

W5 and B6 are natural, but then W7 and B8 used to complete the basic variation before AI brought new insights into the game. The idea is here for W7 to protect against a placement at A while B8 makes a loose connection with two keimas.

If the marked stone is not present, this variation has been evaluated as bad for Black. When White plays around black+circle herself, theinfluence of the black wall is reduced.

AI variation  

AI has improved upon the former, first by dropping to W5 instead of W7 in the previous diagram. This move aims to either destroy Black's left side territory, or require Black to spend another move. Next B6 emphasizes the strength of the wall. W7 and W9 aim to break out of the corner into the right side, or again force Black to spend another move. Having obtained strength with his wall plus extension, Black then usually leaves the area. The focus is not so much on moyo building anymore.

Dropping back  

Extending to W1 was already known prior to AI but White would still drop back at W3. If B4 focuses on the left side territory, White could cut like this later. The moves to White 11 (at a) are one possible continuation.

The old joseki  

The old joseki in this cae 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.

Slightly out of style  

W4 is another joseki move. The sequence to W10 is forced, after that Black can choose to build thickness with a or fight immediately with b. a has been 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.

Influence (6 connects)  

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 A that is hard to deal with. For example:

Disaster for Black  
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:

Picnic ko for White  

If Black decides to fight:

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.

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.

Good for white?  

White can also answer here. The Black stones on the left make inefficient shape. The circled stone on the star point ends up looking inefficent. White retains significant endgame aji 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.

See also

4-4 point one-space low pincer invasion, block last edited by Dieter on November 28, 2023 - 14:29
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