4-4 point low approach low extension
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The 4-4 Point Low Approach Small Knight Extension is one of the most common and popular responses to the 4-4 Point Low Approach. Joseki that branch from this position are played at all skill levels, and the slide joseki is typically one of the first joseki that beginners learn.
The small knight's extension is very solid and emphasizes a balance of territory and influence. White can slide and share the corner territory, but Black's stones are very robust and can easily form a secure base. Black might ultimately claim less corner territory compared with the 4-4 kick joseki (greedy) or classic versions of the 4-4 attachment joseki (gote), but Black is likely to stay strong and retains initiative (sente) with this extension, which are valuable qualities that will help the player keep momentum later in the game. For this reason, the small knight's extension is the local response that is traditionally favored by professionals and strong AI programs on an empty board during the opening.
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Moves are listed by frequency in professional games, which is sensitive to whole-board position. Note that the professional game database includes all historical games, so the frequency of the AI attachment appears low, even though it is especially common since the AI era. Bolded moves are commonly considered joseki.
- a, Slide - (joseki) (common) (beginner)
- c, Three-Space Mixed Extension - (joseki) (common) (beginner) (kobayashi fuseki)
- b, Tenuki - (joseki) (common) (intermediate) (AI favorite)
- h, Attachment - (joseki) (common) (AI favorite) (intermediate)
- d, Mini-Chinese Extension - (joseki) (common) (intermediate) (mini-chinese fuseki)
- e, Two-Space Mixed Extension - (joseki) (kobayashi fuseki)
- f, Jump - (joseki)
- l, Shoulder Hit - (joseki)
- g, Three-Space Low Extension - (joseki)
- i, Two-Space Low Extension - (joseki)
- n, 3-3 Invasion - (rare) (situational)
- m, One-Space Alternate Approach - (rare) (situational)
- j, Two-Space Alternate Approach - (rare) (situational)
- k, Four-Space Mixed Extension - (rare)
- o, Probe - (trick play) (ko threat)
Asking for the Corner
Asking for the corner is a move that White plays to settle their group quickly, and it is the most common local continuation. Black may opt to defend the corner or play for the outside. Typically (but not always), Black will refuse to give away the corner (see: "Corners, then sides, then center"), and both players will share a part of the corner while mutually establishing strong bases. This is considered an "even" result, which is why this is one of the first joseki that many players learn.
- The slide joseki is traditional, simple, and one of the first joseki that beginners learn. Despite the fact that it has fallen in popularity in recent years, it is still a good move, and there are professionals who still play the traditional joseki even after the AI revolution. The difference between the slide joseki and the AI Attachment is subtle and less than one point difference in projected score, and both joseki are practically and functionally similar in amateur play.
- The AI attachment was historically viewed as a vulgar move before the AI revolution. Strong AI programs prefer the attachment over the slide because it is a forcing move that Black cannot tenuki from. In recent years, the AI attachment has largely replaced the slide joseki in high-level amateur and professional play. Several complicated variations can branch from the AI attachment, but they are essential for any intermediate amateur go player to know due to the overwhelming popularity of AI joseki in modern go.
See main article: 4-4 point low approach low extension, tenuki
Modern go emphasizes speed and corners, so tenuki (23% ) and the AI attachment are by far the most popular choices. In fact, in professional games since the AI revolution, tenuki is in fact more popular than playing locally. Many professionals play the low approach as a probe to see how Black will respond.
While it may be difficult for weaker amateurs to grasp, the approach stone is very flexible, and a skilled player has many ways to handle the stone even if Black gets another move. Since this is the case, Black will often play at other big areas of the board until one of the two players choose to return to the local position later.
Making an Extension
Three-Space Mixed Extension
Two-Space Mixed Extension
Three-Space Low Extension
Two-Space Low Extension
Extensions from the approach stone have steadily increased in popularity during modern go. While they are typically not the top choices recommended by AI, human professionals have experienced extensively with fuseki like the Kobayashi Fuseki and the Mini-Chinese Fuseki. These rapid extensions favor speed and aim to develop a framework. Loose frameworks are not secure, and while they threaten to develop a large moyo, the opponent has opportunities to invade and reduce later in the game.
- The three-space mixed extension is a common extension seen in go. While it can still be invaded (see: Three-space extension invasions), it emphasizes influence. It is frequently played as part of the Kobayashi Fuseki.
- The mini-chinese extension is seen as part of the Mini-Chinese Fuseki
- The two-space extensions are played when White wants to develop a position on the side, often when Black is strong in the area or if the outside is more valuable than the corner. If Black chooses to kick, White's base may be a little cramped, but it is strong.
- The three-space low extension is one of the smallest frameworks. It has a potential invasion point, but the move is regularly played by professionals.
White may opt to seek influence or develop a moyo after approaching the corner. Traditionally, these might be considered questionable and situational moves, as White has not established a base and may come under attack. Influence is not territory, and it can be ill-advised for White to commit to a single game strategy. The value of a one-space jump can easily be negated with an effective moyo reduction later in the game. However, strong AI programs typically do not criticize these moves as much as human go teachers.
- The one-space jump aims to develop a moyo on the upper side.
- The shoulder hit is a move that was recently popularized by AI. It can be conceptualized as a gote reduction sequence played during the opening, but it is a little difficult for me to understand. Some professionals have attempted to mimic this move, but not necessarily to great success (winning ratio 36%) . The winning ratio appears to be better when professionals treat it as a sente reduction exchange before tenuki elsewhere on the board. -- yuzukitea (4k)
One-Space Alternate Approach
Two-Space Alternate Approach
- White can invade the 3-3 point and live small in sente. On an empty board, this is not advised, as the influence that Black gains on the outside is too good. Strong AI programs also agree with this sentiment. Furthermore, if White wanted the corner, they should have invaded the 3-3 point to begin with rather than approaching first. However, in the right situation, the 3-3 invasion can be a good move if White has an existing position on the left side.
- In rare situations, White may opt to change directions and approach from the opposite side. The one-space alternate approach is common in handicap games. The two-space alternate approach is not joseki, but it is actually more common in professional games as a fuseki involving the the 3-4 point high approach, inside contact, hanging connection joseki.
The AI joseki allows Black to take influence
AI Joseki (Influence var.)
Ever since the AI revolution, many amateur players copy AI joseki without fully understanding them. Whether AI joseki or traditional joseki is "better" for amateur kyu players is a controversial subject, as strong AI programs are generally better at neutralizing the value of influence than beginners who do not have developed strong invasion, reduction, and whole-board judgement skills. AI scores typically skew in ways that value influence less than traditional human assessments of positions.
A critical detail for kyu players to understand about the AI attachment joseki is that it trades influence for strength. The joseki allows White to settle and create a strong group, but Black has the choice to build a wall in sente. White should not play the AI attachment joseki if they are afraid of Black obtaining a wall, or if the wall appears to be good for Black.
Ultimately, the difference between the slide joseki and the AI attachment joseki is a projected score of 0.3 points. Unless you are playing perfect endgames and never making mistakes, a 0.3 point difference is not a mistake and should not be a significant factor in choosing joseki. At an elementary player's level of understanding, both joseki are equivalent in value.
Rather, the AI joseki should be regarded as the AI's style, just as Takemiya Masaki's style is to play cosmic go. An amateur attempting to mimic Takemiya's style without understanding his full set of abilities is unlikely to enjoy the same level of success.
- Reddit: 4-4 Attachment Joseki versus "Traditional" Play (2020)
- (Blog Post) u/matagen (3k): Resigning In Sente: 4-4 Low Approach - Slide or Attach? (2021)
-  Frequency statistics were obtained from Waltheri's Go Pattern Search using the full database restrained to a local search (accessed August 2021). Due to the weighting of older games in the database, the 3-3 invasion appears to be less frequent than it actually is in recent years. With the search restricted to contemporary/post-AI games, 20-30% of 4-4 approaches are 3-3 invasions.
-  AI score estimates were obtained from katrain (v1.9.3) using a Nirensei board with two star points occupied by each player. AI score estimates can vary widely depending on the board position and software version, and should be taken with a grain of salt. Notably, the point values of many joseki on this page differ by less than a one point, indicating that many of the listed joseki are indeed playable at all levels.