Beginner Exercise 30 / Solution

Sub-page of BeginnerExercise30

throw-in ko

[Diagram]
setting up ko  

This strange shape rarely occurs in practice, but is interesting enough to discuss.

W1, play on the point of symmetry, sets up a throw-in ko at a. On the other hand, it gives Black a chance to start his own throw-in ko at b.

If White starts the ko and win it, she gets 28 points of territory. If Black starts the ko and win it, he gets only 8 points of territory. So the burden is much heavier on Black - in most cases, White should play W1 and wait for an appropriate moment to start the ko. That will considerably restrict Black's play elsewhere - he can't worsen the ko threat situation.

(The position is somewhat similar to a more common shape called "ten thousand year ko" in nature.)

[Diagram]
nearly waste of a move  

And strangely, neither side can erase the ko possibility in one move. B2 is not advisable - it doesn't stop White's throw-in at a. Worse, B2 increases White's territory (or decreases Black's territory) after the ko fight by 1 point.


seki possibilities

[Diagram]
Black to play  

If it's Black's turn, B1 and W2 make it seki. (W2 is an endgame play worth 7 points in gote.)

[Diagram]
White to play  

W1 forces B2 - else White plays there and wins. This abandons the ko possibility which is normally advantageous for White, though it may be played as a ko threat or game-end procedure.



Beginner Exercise 30 / Solution last edited by hnishy on August 30, 2024 - 10:37
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