Lee Sedol - Gu Li Jubango, game 4

    Keywords: Game commentary
[Diagram]
Moves 1 to 10  

B7 completes an opening pattern by Black known as the micro Chinese opening. W10 would ordinarily be at a.

[Diagram]
Moves 11 to 20  
[Diagram]
Moves 21 to 30  

By B7, most amateurs will feel that White's influence at the bottom is strongly reduced by Black's three stone formation there, while Black has made a big side territory so that the opening is favourable for Black. However, An Younggil from gogameguru states that professional evaluation of this situation is even, because White has created a thick group in what was formerly Black's sphere of influence and Black's three stones are weaker than they appear.

[Diagram]
Analysis of the bottom  

For example: White can atach underneath and cut off a stone (a-b-c follow). As Black can then enter the corner at d, this may not be a good scenario for White. (I am an amateur myself and I largely prefer Black here)

[Diagram]
Resist  

Incidentally, if B5 pulls out, then White captures two stones at the right side. The question is now if B9 can capture the 5 white stones. Black's corner is weak though and the outside has many cutting points. With black+circle having become meaningless, the trade is not good for Black.

[Diagram]
Moves 31 to 40  
[Diagram]
Moves 41 to 50  
[Diagram]
Moves 51 to 60  
[Diagram]
Moves 61 to 70  

B3 tries to develop a moyo while attacking the shape of the white group below. White doesn't respond to the pressure below but instead plays W4 to either revive the corner or achieve the connection at W8 and destroy the moyo potential. To understand why Black can't cut with B7 at W8, see next diagram:

[Diagram]
Moves 61 to 70  

After B1, W2 and W4 connect into Black's territory. Black cannot cut at B5 here because the corner will be captured. This means White can effectively separate the corner. The game result is painful but less destructive.

[Diagram]
Moves 71 to 80  

In his preliminary analysis, An Younggil finds W6 (76) to be questionable and recommends a instead (see next diagram).

[Diagram]
Large endgame  

W1 is the illustrous six point double sente diagonal. Assuming it is sente for both players, meaning it either undermines the life of a group or threatens to destroy a territory which is in itself larger than the points they are fighting for at this stage of the endgame, the difference between either player occupying this point, is 6 points, given the remainder of the endgame.

unkx80: Quite a bit bigger than 6 points, because Black actually attaches at b instead of playing at W1.

The first question is now why this move would at this stage be preferable to W76, which is a move with opening or middle game flavour, as it claims a hitherto loosely claimed territory, while pressuring Black's group.

Another question is why this would be so at this moment in time. This question is a bit easier to answer: Black has just reinforced himself at the bottom, so the value the pressure at W76 contributes to its overall value is lower.

That probably helps understanding why the suggested W1 here is better: it puts pressure on Black's last weakish group. If Black answers locally at a then White gets the move indeed in sente and once committed to this eyespace, a move at b is likely to be sente too.

If Black plays in the centre, then the territory made by his top group has become very small, a and b being almost equivalent. Also, attacking that group in the centre may allow him to make more territory at the left side.

[Diagram]
Moves 81 to 90  

According to An Younggil, W2 here was more than questionable: it was a mistake. Given the above analysis we can understand that playing at the top would help the left side or be big in itself, whule W2 appears to be single minded territorial play.

The W8-B9 exchange helped Black to remove any aji in the corner. So, why was it played?

[Diagram]
Moves 81 to 90  

Black may cut and squeeze. If W2 at W10, Black gets a free atari at a.

[Diagram]
Moves 81 to 90  

unkx80: Well, more than that: B5 can pull out.

[Diagram]
Moves 91 to 100  
[Diagram]
Moves 101 to 110  
[Diagram]
Moves 111 to 120  
[Diagram]
Moves 121 to 130  
[Diagram]
Moves 131 to 140  
[Diagram]
Moves 141 to 150  
[Diagram]
Moves 151 to 160  
[Diagram]
Moves 161 to 170  
[Diagram]
Moves 171 to 179  

Lee Sedol - Gu Li Jubango, game 4 last edited by Dieter on May 10, 2014 - 16:05
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