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LargeAvalanche

Referenced by
DoubleKo

 

Large Avalanche Turn Inward
  Difficulty: Dan level   Keywords: Joseki

[Diagram]
Diag.: Large Avalanche: The inward turn

Black 1 is an invention of Go Seigen, and was first played in a game against Takagawa in the League of the 'Strongest Player' tournament in 1957. Its main idea is that if white answers with 2 here, black next turns at 3, and after some standard variation of the outward turn has been played, the exchange of black 1 for white 2 will have given black two free points compared to playing at 3 directly. Of course, for a professional player to lose two points without any compensation is unthinkable, so this white 2 in general is not played.


[Diagram]
Diag.: The start of the joseki

To avoid the variations as mentioned above, white exchanges 2 for 3 before playing at 4. The moves to 7 invariably follow.


[Diagram]
Diag.: A mistake

White 2 is joseki, but white 4 is a mistake. Black 7, making Miai of 8 and 9, brings white in an uncomfortable position. If played correctly, white will manage to save his three stones and live, but while white is only making two eyes, black will get superb influence.


[Diagram]
Diag.: The joseki continues

Although there have been attempts with different moves, the sequence from white 1 to white 7 here is by far the most common.


[Diagram]
Diag.: A variation

The main variation of the sequence above, is the one where white 3 is played on the top as shown here (sometimes white 1 is played at 3 already, followed by black 2 and white 1). White accepts that there is a chance of losing his three stones at the left, and takes influence at the top instead. Black next can choose among A, B and C; I will give one possible continuation for each. As far as I know, no standard joseki exist yet for this variation.


[Diagram]
Diag.: The vital point

White 2 is forced, after which black 3 is one possibility. White 6 proposes an exchange (see the next diagram) with each player capturing some stones, but black refuses, and fighting will continue on the left side. Black has some very bad aji in the corner though, white being able to set up an ApproachKo here with white A.


[Diagram]
Diag.: Black connects

Black 1 threatens the white stones on the left, and after white 4 things are resolved peacefully, with both players capturing some stones.


[Diagram]
Diag.: Black extends

After the cut with black 3, black captures two stones. Black has taken about 20 points of profit in the corner; white will have to make up for that through his advantage in the center fight.


[Diagram]
Diag.: A black variation

For black, a variation that has been tried is this black 1 instead of black 4 in the last diagram of the main variation. White 4 is the key move here. It creates the ApproachKo (also mentioned above) of white A, which makes this variation problematic for black.


[Diagram]
Diag.: Back to the main line

After the main line, black can play A, allowing white to extend along the left side, or black B, preparing to play on the left side himself, or he can play tenuki, probably making preparations to sacrifice his three stones. In the corner, the three white stones have been captured, but there is still some important aji left.


[Diagram]
Diag.: Double ko

If white plays 1 and 3, black should not play 6 immediately, because in that case white will play 4. This creates an ApproachKo, which in this position is a very good result for white. Instead, black should exchange 4 for 5 first, then play 6. Now white is captured because of double ko. However, this also means that white has an unlimited source of ko threats here, so she will win any ko worth less than about 30 points anywhere on the board.


[Diagram]
Diag.: A sente move

After white 1, she again threatens an ApproachKo, but black can avoid it again, this time by playing at 2. However, after these moves, white 3 is almost sente, because a follow up at A threatens to connect underneath. Having the possibility to play white 3 in sente gives white an advantage in any fighting that might break out on the top.


[Diagram]
Diag.: The basic variation

Black 1 is the most common continuation for black. White almost invariably answers by making a base for her left-side group with 2. The moves to 6 may be considered the standard continuation of the joseki. Instead of white 6, white A-black B is also possible. For the variation where white plays 4 at C, I refer to Ishida.


[Diagram]
Diag.: A special strategy

Black 3 denotes some special strategy. White 4 is a natural answer: White plays the point that black neglected to play.


[Diagram]
Diag.: Game example

The reinforcement of white 6 was necessary because the aji of black A was too menacing. Played between Rin (black) and Ishida for the 1971 Honinbo title.


[Diagram]
Diag.: An aggressive move

Black 1 is a more aggressive move. Black intends to build up strength here, then make a checking extension on the left side. White 2 is the most common answer, but sometimes white plays the more aggressive move of white A. After black 3, several variations are possible.

-- AndreEngels (Feel free to correct on or add to this page, but please do make clear where the changes have been made)



This is a copy of the living page "Large Avalanche Turn Inward" at Sensei's Library.
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