Ko fight example from a pro game - 1

  Difficulty: Intermediate   Keywords: MiddleGame, Ko, Game commentary

The following is an example of a ko fight from a top professional game, namely game 1 in the final for the Samsung Cup edition 2011, between Gu Li (Black] and Won Sungjin (White).

[Diagram]
Moves 139 to 140  

The situation in this game is that White has chased a big black group all over the centre into the left. Black has scrambled to make a ko in the corner. Against B9, White cannot connect at a. Instead, he throws in at W10, putting Black in atari. The ko fight can start. The ko is a direct ko for White but an approach ko for Black: count the remaining liberties of each group (circles and triangle).

[Diagram]
Moves 141 to 145  

B1 takes the ko. W2 is not a ko threat: it connects the White stones on the left by capturing three cutting stones, so that, IF Black would win the ko, the capture of the large black group in the middle would not be affected. In effect, White has reduced the size of the ko: the stake of the ko is reduced to the upper left.

B3 is the first approach move in the approach ko. Now the ko has become a direct ko for both, as said, with lower stakes. W4 captures and now Black plays a local ko threat with B5. He threatens to make more liberties there, winning the fight.

[Diagram]
Moves 146 to 150  

White throws in again, restoring the atari and Black takes back the ko. There are no more local ko threats, so White plays the first ko-threat elsewhere. W8 threatens to destroy the right side. B9 responds and W10 takes back at white+circle.

[Diagram]
Moves 151 to 156  

And so a common ko fight develops, with B1-W2 and W4-B5 both being threats to turn the tables elsewhere, then taking back the ko with B3 and W6 respectively.

[Diagram]
Moves 157 to 160  

The ko fight continues with B7-W8 another threat to bring the central group back to life. B9 takes the ko. W10 now calls for a response at a but ...

[Diagram]
Moves 161 to 162  

... Black resolves the ko with B1 and captures the corner. White now cuts up the bottom and the game continues for a little while, until it becomes clear that the damage done is too big for Black to bear and he resigns.



Probably the game was already desperate for Black when he started the ko and it definitely became difficult when White reduced the size of the ko, solidly capturing the central group, in return for allowing Black to make it a direct ko. Nevertheless this sequence shows a number of key aspects of ko and how professionals manage the dynamics of a game in which a ko develops.


Ko fight example from a pro game - 1 last edited by Dieter on December 12, 2011 - 09:58
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