3-4 6-4 Enclosure

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The two-space high enclosure, also known as the AlphaGo enclosure, is a corner enclosure that was popularized by AI. It emphasizes outside influence at the expense of leaving the corner territory easily invadable. In many circumstances, Black is willing to take a local loss in exchange for benefits elsewhere on the board. This enclosure is very sensitive to the overall board landscape and a ladder, and it has many complicated variations that can result in fighting. Stone efficiency is an important consideration, and in many cases it can be inefficient for Black to invest additional moves to defend the corner after playing this enclosure.

Classically speaking, this enclosure was the rarest of the four enclosures. It does not appear in Essential Joseki, Enclosure Josekis, Ishida's Joseki Dictionary, Keshi and Uchikomi - Reduction and Invasion in Go, A Dictionary Of Modern Fuseki, The Korean Style or Kihon Fuseki Jiten. There is some discussion of this shimari in the Japanese book Shimari no Gihou (Shimari Techniques) by Ishida Yoshio 9p, published in 2002 by Kawade Shobou Shinsha, ISBN 4-309-26570-7. ^[1]

Notes from a reddit baduk topic^[2]: "

The two space high enclosure to komoku is a fast move. It is not trying to take the corner territory fully and you should not expect to have it always just because of an enclosure. From the bot variations I have seen, you often get approached low keima to the 6-4 enclosure, after which it is often a key point to play away and take the star point on the side, similar in concept to the sanrensei. Then the alphago attach at 4-4 joseki ensues, during which black builds a wall while white gets some territory. I'd attach an sgf but eidogo is down. This is the way master played in the games vs alphagozero a lot of the time. So big main point is that if u get approached, u can tenuki into influence. It's not for territory, but for balancing influence. If you don't get approached u can of course try to make a territorial framework.

I'd say the main advantage, and why bots like it so much, is that it is extremely balanced between influence and territory. Basically you have miai with the move. If the opponent goes at you with low keima approach, he indicates he wants territory, so u go into the influence var. If opponent approaches from the other side that faces your enclosure 'wall' then you can play the other 3-4 to make a strong kosumi territory shape with a keima attached to it that helps reduce the opponents influence. In other words, I think it's a balanced, flexible, miai oriented move that gives you options on how to respond. Comparing it to the small knight enclosure, you see that that enclosure takes territory more tightly, but can be bullied by forcing moves, so it is way less flexible. The same can be said of the large knight enclosure to a lesser extent. My perception is that the 6-4 enclosure is an 'if you go that way, I go this way' sort of move whereas the other enclosures lean more towards 'I want this don't take it from me!' Two track vs one track."

Table of contents Quick Navigation Overview of White Continuations Normal Approach Opposite Approach Attachment Invasion Overview of Black Continuations Discussion The extension is big When to play the one-space low opposite approach? When to play the two-space low opposite approach? When to attach directly at the 4-4? History See also 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.

White to Play  

• a, AlphaGo Enclosure, Small Knight Approach? - (common) (intermediate) (AI favorite)
• c, AlphaGo Enclosure, One Space Low Opposite Approach - (situational) (intermediate)
• e, AlphaGo Enclosure, Two Space Low Opposite Approach - (situational) (intermediate)
• f, AlphaGo Enclosure, 4-4 Attachment - (situational) (advanced)
• b, AlphaGo Enclosure, Hoshishita Splitting Move - (common)
• d, AlphaGo Enclosure, Hoshi Splitting Move - (common)

Black to Play  

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Overview of White Continuations

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Normal Approach

Tenuki	Pincer
Tenuki, Attach	Tenuki, Attach

Opposite Approach

Attachment

Invasion

Overview of Black Continuations

Discussion

The extension is big

When to play the one-space low opposite approach?

When to play the two-space low opposite approach?

When to attach directly at the 4-4?

History

[1] Bob McGuigan: In his book Shimari Gihou referenced above, Ishida Yoshio gives quite a bit of information about this shimari and how to play against it. It came to notice during the Shin Fuseki period but now is not widely played. However, it is coming back a little due to the present-day emphasis on speed. Ishida devotes some 60 diagrams to the analysis of this shimari. Speaking of strategy, Ishida feels that from Black's standpoint the timing of when and how to defend the corner territory is a difficult issue. From White's perspective, helping Black solidify the corner territory is forbidden. White's goal is to exploit the weakness of Black's fourth line extension. Invading at in the following diagram is one idea. The most common response is followed by .

One idea  

Another response by Black:

A different response  

This tends to lead to White living in the corner and Black building strength on the outside or facing the upper side.

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See also

• 3464 enclosure statistics
• PJQ 6

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References

• [1] Frequency statistics were obtained from Waltheri's Go Pattern Search using the full database restrained to a local search (accessed September 2022).
• [2] https://www.reddit.com/r/baduk/comments/agtcli/comment/ee9y2ow/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button