Large Avalanche Turn Outward

  Difficulty: Expert   Keywords: Joseki

Table of diagrams
The large avalanche: turn
Black offers a sacrifice
White jumps out (reject sacrifice)
White jumps out: continuation
White jumps out: Black’s ko to save the top
White jumps out, atari variant
White jumps out, Black takes corner
Obsolete: Black does not sacrifice
Black does not sacrifice: continuation
Black does not sacrifice: alternative
Black does not sacrifice: alternative: continuation
Variant: White captures but Black too thick
AlphaGo’s new move

[Diagram]
The large avalanche: turn  

After B1, the moves to W6 are considered the best continuation, although there is some variation possible, especially for W4. After this, Black has to choose whether to save or sacrifice his three stones.

Jonathan Cano: I've created a problem for a non-joseki variation on W4, at Large Avalanche Turn Outward Problem. The problem begins with W4 at B5.

[Diagram]
Black offers a sacrifice  

Nowadays, B7 is considered the joseki move. Black allows White to take his three stones and the corner, making influence in return. W8 accepts this exchange. The sequence to B11 is the current joseki. In the past is was more common for white to play atari at B11 instead of W10, followed by black a, white W10, black b. After the joseki, black can exchange c for d to cut white off from the center, but black might prefer to force with e rather than c, and so keeps both in reserve until he knows which is best.

[Diagram]
White jumps out (reject sacrifice)  

If White does not accept the sacrifice, as seems to be more common nowadays, she jumps out at W8. If white answers B13 at a, black captures the corner stones at b. In this case white does not have an immediate forcing move on either side, so she usually prefers to move the fight to the top as shown in the next diagram.

[Diagram]
White jumps out: continuation  

With W14 and W16, white tries to get some forcing moves in. Black may accept with B17 at B21, but is once again more likely to go for a sacrifice with B17. After W20, the black group at the top is captured, but only in ko, and black has considerable counterplay, starting at B21. Note that a is black's sente, so the three white stones have little chance to move out.

[Diagram]
White jumps out: Black’s ko to save the top  

This is the ko that is left in the position. Alternatively, black can use the corner aji to force on either side.

[Diagram]
White jumps out, atari variant  

White can also play atari at W18 before the attachment at W20 (W18 in diagram 4. After W26, the fighting obviously continues, but the position has not occurred often enough in professional games for me to discern a joseki.

[Diagram]
White jumps out, Black takes corner  

Instead of pushing at a (B13 in diagram 3), black can also take the corner with this B13. White cuts with W14, and another fight ensues.

[Diagram]
Obsolete: Black does not sacrifice  

Saving the black stones with B7, rather than sacrificing them with a play at W14 (B7 in diagram2), used to be joseki.

[Diagram]
Black does not sacrifice: continuation  

This used to be a popular joseki around 1950. Nowadays the fact that Black has to play two moves (B9 and B11) to capture the corner is regarded too large a disadvantage.

[Diagram]
Black does not sacrifice: alternative  

B9 seemed to improve on a black play at W14 (B9 in the previous diagram), allowing Black to take the corner with one move, until the counter-measure of W12 was discovered.

[Diagram]
Black does not sacrifice: alternative: continuation  

This is considered good for White because Black still has to take the three stones off the board. So Black's territory is rather small, while White has been able to play on both sides. If Black plays B19 at a, White can create a ko, while if Black does not play B21, White plays at b and Black dies outright.

[Diagram]
Variant: White captures but Black too thick  

If White plays W4 in the main diagram at W4 here, White can capture the three stones whatever happens. However, this gives Black too much thickness (note that Black a next makes a ponnuki in sente).

[Diagram]
AlphaGo’s new move  

This new continuation was played by AlphaGo Master (e.g. in its 29th Tygem game, [ext] against Mi Yuting), and it is said that B5 is entirely new.


Authors:

  • Andre Engels
  • (add your name if you make a significant contribution to this page)

Large Avalanche Turn Outward last edited by Uberdude on April 24, 2018 - 18:58
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