Ko fight example from a pro game - 3

  Difficulty: Advanced   Keywords: Ko, Game commentary
[Diagram]

start of ko

This is a game between Zhang Li and Huang Yizhong in 2005. White invites a ko with W6, which is necessary to fight the capturing race in the corner. B9 starts the ko.

[Diagram]

B8 at C19

W1 is the first threat and it is a local ko threat. B4 is also a local threat. Next W5-B6 prepares W7 which is necessary to continue the ko. B9 is another local threat.

[Diagram]

B4 at black+circle, W7 at W1

B2 is a local threat and W3 must respond again. W9 seems to finish the ko, but ...

[Diagram]

W6 at white+circle; W8 at B3

Black throws in at B1, a tesuji that reminds of the two stone corner squeeze. B3 then takes the ko, which has become a two stage ko. Finally, W8 at B3 resolves the ko.

Tapir: Was W8 at B3 or at the spot marked in the diagram. Either move resolves the ko though.

Incidentally, the last local threat, at W4 is worth a discussion:

#1 #2
[Diagram]

tobi W3

If black+circle has resolved the ko, (below treatment can be cleaned up a little)

tderz: I think W3 is good (even better).
The normal White a threatens the same and also involves W3.
I wonder whether one could say that one is better than the other.


[Diagram]

internal ko threats

tderz: [1] B6, W7 and B10 are miai - if B6 at W7, then W10.
White wins the semeai by 2 moves AND the ko at x is still good aji for white (bad for black).
In the game Black got two moves in the upper left corner instead.
B4-W7 is a bad exchange - it loses one liberty.

[Diagram]

internal ko threats

tderz: White answers with W5 to keep the nice ko aji in the corner. White wins by 2.


[Diagram]

stretch + atari

tderz: [2] a (W7) and b (B6) are miai.
It's 4 to 4 liberties (kmnl & pqrst, the exchange x-y is forced and does not count) with white to move.

White wins here (only) by one liberty.

Answer: Black did here not make the bad B4-W7 exchange in [1] above! (that cost him the 1 liberty!)


This is a copy of the living page "Ko fight example from a pro game - 3" at Sensei's Library.
(OC) 2012 the Authors, published under the OpenContent License V1.0.
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