4-4 Point Low Approach Low Extension, Contact, Atari Down, Connect

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The 4-4 point low approach low extension, contact, atari down, connect is part of the most common sequence in the AI 4-4 small knight approach joseki.

It is a calm, balanced move that has few weaknesses and reiterates Black's interest in influence towards the left side of the board. It is possible for White to capture the corner and live small in this position, but this is usually inferior for White in most circumstances.

This position is urgent and White cannot tenuki.

Table of contents Quick Navigation Overview Keep Side Capture Corner Discussion When to capture the corner? References

Quick Navigation

Moves are listed by frequency in professional games^[1], which is sensitive to whole-board position. Bolded moves are commonly considered joseki.

Connect Joseki  

• a, Connect (~98%) - (joseki) (common) (AI favorite)
• b, Atari (~2%) - (joseki) (situational)

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Overview

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Keep Side

Staying connected and retaining the side is the natural move. This should be the default unless there is a compelling reason to play anything else.

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Capture Corner

Corner Capture Variations
Gote Var.	Descend Var.	Sente Var.	Sacrifice Var

Capturing the corner is usually considered inferior for White in most circumstances. It is infrequently played by professionals (~2% frequency)^[1], although from an objective perspective it is less than a one point loss on an empty board according to Katago. Still, it is probably best regarded as a situational move that is most commonly seen in the context of a pincer or when the top side of the board is uninteresting.

• Capturing the corner can be considered gote. It is common and traditional for Black to play for sente as depicted in Dia 1. However, Black's shape is a little thin, and there may be a chance for White to counterattack in the future. The AI Weiqi Joseki Dictionary says that this is slightly inferior for Black, but it is the most common sequence played in professional games.
• If Black descends with (Dia 2), Black can play for thicker shape, but it gives White an opportunity to play for sente. at a plays for sente as depicted in Dia 3. at b or c is typically gote, but it gives White a stronger follow up against Black in the future. In particular, the marked stone is vulnerable to being cut in the gote variations.
• The Sente Variation (Dia 3) has some weaknesses for White. If Black plays w-z, this is sente against the corner and White must respond. As a result, Black's outside stones are more resilient.
• There is a noteworthy Sacrifice Variation depicted in joseki books. After Black descends with at w ( in Dia 4), this pattern gives black a wall facing both sides in exchange for sacrificing three stones. However, there is one cutting point at the apex of the wall at . The AI Weiqi Joseki Dictionary says that this is slightly better for Black.

Discussion

When to capture the corner?

Tsuruyama Atsushi (B) vs. Ko Iso (W) (2019)  

yuzukitea: Tsuruyama Atsushi vs. Ko Iso (2019) is an example of a game where it is advisable for White to capture the corner.

In this board position, the top side of the board is dull beyond imagination. There is no good potential for territory for either player.

Black's corner in the upper left is completely solid. White has a dragon on the left side of the board, but it is relatively resilient due to its strong shape towards the center of the board. The tail of the dragon could use a better connection, but it can easily be fixed in one move if the right circumstance arises. Overall, there is not a compelling reason for White to create a small base on the top side of the board, especially as any potential in the area is already undercut by Black.

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References

[1] Frequency statistics were obtained from professional games downloaded from kifudepot? (Jan 2016 - Nov 2023) constrained to a local search.

[2] AI Weiqi Joseki Dictionary (2021) by Jiang Weijie