4-4 point diagonal attachment, low corner enclosure

  Difficulty: Advanced   Keywords: Joseki

Table of contents

Original discussion

In the 4-4 point diagonal attachment joseki, it is not recommended to play the 4-4 point low enclosure at B1. In most cases, Black should play the one space jump at a instead.

Reason 1  

One reason is that W1 becomes a good move, pressing Black low. Then White can look forward to the bad aji at the attachments at a and b, as well as the 3-3 invasion at c.

Reason 2  

Another reason is that when the outside White stones are strong enough, then White can look forward to attaching at W1 and then playing W3 at the 3-3 point[1]. White can look forward for reducing Black's territory or increasing White's influence, or both.

Ladder relationship  

Specifically, the ladder after B6 should favour White in order to play the W1, W3 combo.

Not possible to live  

In normal situations, it's impossible for White to invade the 3-3 point directly. This sequence is the most common variation to kill the White group.

(However, White does have the choice of fighting instead of trying to live in the corner-- see 4-4 point low approach low extension tenuki, diagonal attachment, 3-3 invasion for more details.)

(5d analysis by Minue)

Correct plays(locally speaking) for black are showed in following 2 diagrams.

Common play of black. (1-1)  

The intent of B1 is to defend B's corner securely. In this diagram, B3, B5 moves might(may?) be put off, depending on a condition of whole board situation.

Common play of black. (1-2)  
Common play of black. (2-1)  

Another way to play is B1,which is somewhat modest. In this case, it is often seen for w to invade at 3.3 immediately.

Common play of black. (2-2)  

Of course, this is most peaceful sequence.

Evaluation with KataGo

4-4 point diagonal attachment, low corner enclosure  

This is the basic diagram. There are several questions to answer here:

  • Is B1 significantly worse than a?
  • How does a pincer stone at B affect the matter?

The evaluation is done using KataGo as a reference.

No pincer stone

All star point opening  

In a symmetrical parallel all star point opening

With a pincer stone

San ren sei  

In case of a Black san ren sei, White's lead is 1.1 to start with. Again, 3-3 invasions of either Black corner are preferred.

An inside approach at W1 loses 0.6 and we start at 0.5. This is our reference for the discussion.

San ren sei  

Interestingly, B4 putting pressure on the white stones may prompt White to treat those stones lightly and approach at W5. Things can become quite heated from that point onward.

With a supporting stone on the side

Outside approach  

Suppose this time that Black has played a (suboptimal) move on the side black+circle. White's approach on the outside W1 will result in this sequence. Traditionally it was considered bad for Black to kick at B2 but nowadays, due to AI evaluation, making White stronger towards an open side is considered playable because Black gets sente.

If instead Black plays low, he'd lose about 0.7 in this position:

Outside approach  

In this case White's stones are considered more resilient, allowing White to take sente. Both a and b are now available.

About the 5d recommendation


KataGo doesn't like B2 all that much. W3 makes a base. Black can indeed gain influence towards black+circle with B4 and B6 but this doesn't offset White's sente.

In a case of synchronicity Michael Redmond has just released this video

[ext] https://www.youtube.com/watch?v=Il7Jt3i9Nl8

4-4 point diagonal attachment, low corner enclosure last edited by Dieter on October 2, 2021 - 12:20
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