3-4 point, high approach, inside contact, solid connection

    Keywords: Joseki, Tactics

Table of contents

Joseki

[Diagram]
Joseki  

The canonical joseki for the solid connection at W4 is as shown, with W6 making a three-space extension from two stones, "completing" the joseki. Here the low extension is shown, W6 may also be played at the high extension at a. The low extension emphasizes territory, while the high extension emphasizes influence. See fourth line vs. third line for more discussion on this aspect.

Depending on the left side, B5 may also be played at b or c, each with its pros and cons. The advantage of B5 here is that it finishes the position in one move.

In older days, B5 at d is also seen (Takahashi Shigeyuki (B) vs. Go Seigen 1936-04-14), but presently it is no longer considered to be joseki. See 3-4 point, high approach, inside contact / discussion about why d is considered to be too wide.

In special cases, B5 may also be played as a pincer at or around W6. See the section on "Black pincer variant" below for more.



Black's alternatives for the extension

[Diagram]
Joseki  

We now discuss the extension of B5, and its two variants a and b.

[Diagram]
One space jump  

The one-space jump of B1 finishes the joseki in one move, with no intention of further expansion along the left side.

[Diagram]
One space jump  

As Black's position is low, subsequently W1 and W3 can expand the top side. Incidentally, Leela Zero suggests B2 may be more efficient at a.

[Diagram]
Diagonal  

The diagonal move at B1 implies an interest in further expanding the left side with a move at B3. Later, Black can play at a for further expansion.

[Diagram]
Diagonal  

As the black+circle stones form diagonals that are compromised by white+circle, in this variation W1 is a common probing move, which aims at Black's cutting points at a and b. As Black can only defend only one of them, White can then decide a suitable follow-up. Note that the timing of W1 and its follow-up moves is important for achieving the best effect.

[Diagram]
Diagonal  

If Black defends on the 3-3 point, then the W1 and B2 exchange allows White to profit in sente, as black+circle is weakened.

[Diagram]
Diagonal  

If B2 defends the outside cutting point, then W3 to W7 obtains endgame profit at the top side.

[Diagram]
Knight's move  

The knight's move of black+circle also aims at further expansion near B3. Without B3, a move at White a will expose the weakness of the knight's move.

[Diagram]
Knight's move  

When Black ignores white+circle, W1 strikes at the waist and cuts Black off.


Black's pincer variant

[Diagram]
A special plan  

Black can play at B1 or a if White's extension frustrates Black plans at the top. (This is bad locally, but may be playable overall.) White's compensation is to fence in Black and create substantial thickness. For both players, knowing how to handle White's thickness is key to playing this variation.

A word about B5: the connection can also be at b. W8 is a little better than c. (Compare with getting ahead with a one-point jump.)

If Black plays atari at B6 instead ...

[Diagram]
A special plan  

... W2 and W4 capture a big corner. W4 at a would be soft. The black+circle stone loses half its purpose.

[Diagram]
Soft  

W4 here is also soft. Black plays a good empty triangle and White has either a cutting point (after White a) or bad shape (after White b).


Invasion patterns

(this section needs review)

Low extension

[Diagram]
Low extension - invasion  

With a checking extension at black+circle, it is possible for Black to invade this three-space extension if White does not defend at a.

[Diagram]
Peaceful  

One possible continuation is that Black connects back with black+circle, while White has a wall. However, this wall is without base, so depending on the remainder of the board, the White group might actually become a floating group.

[Diagram]
Forcing  

Black can choose to force White into bad shape at W6, and take influence with B7, leaving aji at a.

[Diagram]
Resistance  

White can resist with W2. After W8, Black needs to connect at B9. White has influence and sente but the stones are now without a base.

[Diagram]
Fighting  

Black can fight with B5, leading to a whole board fight.



High extension

[Diagram]
High extension  

After the solid connection (circled) and the high extension (squared), Black can invade even without support.

[Diagram]
Invasion  

White's choices depend on the rest of the board. After B7, it looks natural to play a but Leela Zero suggests that b is superior.

[Diagram]
Blocking firmly  

When W2 blocks firmly, Black can play B3-B5 in sente. White needs to cover the cutting point with W6.

[Diagram]
Surrounding loosely  

W2 surrounds more loosely and treats the original solid connection more lightly, giving more importance to overall influence in this variation with W6. After B7 connects, White has sente, which is the major advantage over the previous diagram. Leela Zero gives this a 10% difference.

[Diagram]
Deep Invasion  

B1 is very effective. It threatens to link up at a. If White prevents this with W2, the fight can become very difficult for White after B3. Often, White just defends with W2 at b. After that, Black can treat B1 as kikashi if he likes.

[Diagram]
Deep Invasion  

So White will, in absence of supporting stones, likely choose to take influence with W2 and subsequent moves.



No extension needed?

[Diagram]
Extension not urgent  

One novel understanding coming from the AI revolution is that the solid connection doesn't need an urgent extension. It has more thickness than previously thought. In this early board position for example, Black may choose to enclose the upper right. If W2 then takes away Black's base, B3 defends and Black doesn't seem to be off badly.

If he wants to play on the lower side, ...

[Diagram]
Development  

... Black can develop more aggressively.

[Diagram]
Resistance  

White can resist with this pincer, leading to a double approach pattern in the corner. Again, taking away Black's base doesn't seem as troublesome as previously thought, due to a and the forcing moves of b or c available.


3-4 point, high approach, inside contact, solid connection last edited by 107.210.159.110 on April 22, 2020 - 16:46
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