3-4 point high approach low extension, cross-cut

    Keywords: Joseki

The sequence formerly known as trick play

[Diagram]
Forced sequence  

After B2, W3 is a normal response. B4 is normally played at W7. When B2 cuts here, the continuation to W9 is almost forced.

[Diagram]
Before AI  

Before AI it was believed W7 in the previous diagram should be played as W1 here. AI however thinks this thick terriroty in sente for Black is too good.



There are however many fighting variations

[Diagram]
Peaceful variation  

White gets territory, albeit small, in sente. The confined position was long believed to be inferior but AI has evaluated this more positively for White.

[Diagram]
Pressure  

Black can extend at B1. For a long time this was thought to set up a trap by extending later at a, catching White in a shortage of liberties after b and c. However, AI seems to have found a countermeasure. Up to W10 White plays with the idea to sacrifice the corner and get a favorable position in the center, should Black activate the aji at a.

[Diagram]
Pressure ctd  

Now it's White taking 4th line territory and the corner is still not in danger:

[Diagram]
No capture (B9 at B3)  

After W10 it's Black who suffers from shortage of liberties

[Diagram]
The extension  

On a whole board like this, AI postpones life in the corner, stressing central influence.

When W11 connects at the circled point, Katago sees possible continuations at a, b or c, still not thinking about living in the corner.

Killing the corner is a 20 point swing, but apparently the outside is bigger than that.

[Diagram]
The extension  

The countermeasure of B2 is estimated as ~22% inferior by Katago.



White descends, black hane up

[Diagram]
Black hane up at 8.  

After B8, the players are in for a complicated fight. White can avoid that fight by playing a, but playing a comprises a small loss for white.

See the discussion at BQM186


White atari

[Diagram]
White atari at 7.  

The white atari at 7 is a mistake. Black captures with B8.

[Diagram]
White atari, continuation  

After black captures the stone at 3-3, white can only give atari with W1. After black defends, white has two cutting points. White will defend the upper cutting point at W3, after which black cuts with B4. With W5 and W7, white sacrifices another stone and sets up a ladder. If the ladder is bad for white, this is a disaster, but even if it is good, black is very happy. Black gets a big corner in sente and can look forward to play a ladder breaker later on.


See also 3-4 point high approach low extension, whole board


3-4 point high approach low extension, cross-cut last edited by Dieter on April 2, 2021 - 00:58
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