Large avalanche - turn inward

  Difficulty: Expert   Keywords: Joseki

Chinese: 大雪崩内拐定式 (dxuěbēng niguǎi dngsh)
Japanese: 大ナダレ定石
Korean: -

[Diagram]
Large Avalanche: The inward turn  

This B1 is an invention of Go Seigen, and was first played in a game against Takagawa in the League of the 'Strongest Player' (Saikyo) tournament in 1957.

Its main idea is that if White answers with W2 here, Black next turns at B3, and after some standard variation of the outward turn has been played, the exchange of B1 for W2 will have given Black two free points compared to playing at B3 directly. Of course, for a professional player to lose two points without any compensation is unthinkable, so this W2 in general is not played.

[Diagram]
The start of the joseki  

To avoid the variations as mentioned above, White exchanges W2 for B3 before playing at W4. The moves to B7 invariably follow.

[Diagram]
A mistake  

W2 is joseki, but W4 is a mistake. B7, making miai of W8 and B9, brings White to an uncomfortable position. With correct play, White will manage to save her three stones and live, but while White is only making two eyes, Black will get superb influence.

[Diagram]
The joseki continues  

Although there have been attempts with different moves, the sequence from W1 to W7 here is by far the most common.


[Diagram]
A variation  

The main variation of the sequence above, is the one where W3 is played on the top as shown here (sometimes W1 is played at W3 already, followed by B2 and W1). White accepts that there is a chance of losing her three stones at the left, and takes influence at the top instead. Black next can choose among a, b and c and others; I will give one possible continuation for each.

[Diagram]
The vital point  

W2 is forced, after which B3 is one possibility. W6 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 approach ko here with White a.

[Diagram]
Continuation (11-12-13 at a-b-c)  

Black squeezes with B1 and further to build thickness.

[Diagram]
Black extends on the side  

B1 is the most common variation, after which the variation to B7 is forced. W8 and B9 form the most common continuation. After this, the fighting is not over, but there are no standard variations any more.

[Diagram]
Black extends  

W2 is usually played at W6, which leads to the situation above with a different move order. [1]

After the cut with B3, Black captures two stones. Black has taken about 20 points of profit in the corner; White will have to make up for that through her advantage in the center fight.

[Diagram]
A Black variation  

For Black, a variation that has been tried is this B1 instead of B4 in the last diagram of the main variation. W4 is the key move here. It creates the approach ko (also mentioned above) of White a, which makes this variation problematic for Black.


[Diagram]
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+circle stones have been captured, but there is still some important aji left.

[Diagram]
Double ko  

If White plays W1 and W3, Black should not play B6 immediately, because in that case White will play W4. This creates an approach ko, which in this position is a very good result for White. Instead, Black should exchange B4 for W5 first, then play B6. 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]
A sente move  

After W1, she again threatens an approach ko, but Black can avoid it again, this time by playing at B2. However, after these moves, W3 is almost sente, because a follow-up at a threatens to connect underneath. Having the possibility to play W3 in sente gives White an advantage in any fighting that might break out at the top.


[Diagram]
The basic variation  

B1 is the most common continuation for Black. White usually answers by making a base for her left-side group with W2. The moves to W6 may be considered the standard continuation of the joseki. Instead of W6, White a-Black b is also possible. For the variation where White plays W4 at c, I refer to Ishida.

[Diagram]
A special strategy  

B3 denotes some special strategy. W4 is a natural answer: White plays the point that Black neglected to play.

[Diagram]
Game example  

The reinforcement of W6 was necessary because the aji of Black a was too menacing. Played between Rin (Black) and Ishida for the 1971 Honinbo title.

[Diagram]
An aggressive move  

B1 is a more aggressive move. Black intends to build up strength here, then make a checking extension on the left side. The tough answer at W2 is the most common answer, but white also sometimes plays a, or plays her sente in the corner, starting with b, first. Black builds a wall with B3 to W8, then attacks with B9. If he does not want to make White so strong this way, Black might also play at B9 instead of B5 or B7.

[Diagram]
Continuation  

White attaches at W1 and pulls back. After B4, White can attack with moves like a or b, and both players will go on towards the centre.

-- AndreEngels


[1]

The game at Paris 2005 between FAn Hui and [ext] Csaba Mero shows this:

[Diagram]
Black extends  

Someone commented that the joseki then continues:

[Diagram]
Ladder  

White wins in the corner, but acc to the commentator it all depends on a ladder at B4. I do not yet see it.

[Diagram]
Ladder  

fractic: Kogo's joseki dictionary gives this line. B5 looks very ambitious.

[Diagram]
Ladder  

fractic: If Black does not have the ladder he now has to play a. He'll get the three white stones but White captures Black's lump with b. If Black does have the ladder he can connect on c and since the ladder starting with b no longer works White is devestated.


See also:


Large avalanche - turn inward last edited by Yoshiki on December 12, 2012 - 03:23
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