Ko fight example from a pro game - 6

  Difficulty: Advanced   Keywords: Ko, Game commentary

This example comes from the famous game in which B Hans Pietsch, then 1p, defeated W Yoda Norimoto, 9p, then one of the world's top players, by half a point in the 2nd LG Cup (round 1, 1997-06-27) . The game is commented [ext] here (broken, take [ext] this) by An Younggil of gogameguru, as a tribute.

The ko displays the ideas of enlarge the ko and yield the ko.

Ko starts at W8  

Black has taken the advantage early in the game. White white+circle took a big point so that Black had to launch an attack on the white center right. White tries to make sabaki and after B7, White starts a ko with W8. The first threat is B9, which could kill the bottom with a move at a. W10 responds. Next it would be natural to take back the ko.

Enlarging the ko  

B1 tries to fix the bottom before returning to the ko, but this allows White to surprisingly enlarge the ko at W2. B3 takes the ko and White plays the only local ko threat in this ko. Black is left without ko threats and must yield in this ko. W8 makes life and in effect White has come out of this ko as the winner without giving anything in return (the usual ko exchange).

Why yield  

Suppose Black does play a ko threat, for example B1 here. W2 captures through to win the ko, then when Black executes his threat with B3, a move like W4 (or a or b - this diagram is not pro analysis) will destroy the complete lower right, while Black's compensation at the top is not very solid.

By winning the ko without compensation, White restored the balance in the game. The maneuver allowing him to win the ko was enlarging it so that Black had to yield as to minimize his loss.

Ko fight example from a pro game - 6 last edited by RobertPauli on December 27, 2018 - 16:41
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