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BeginnerExercise5
BQM47

 

Beginner Exercise 5 Solution
  Difficulty: Beginner   Keywords: Problem

[Diagram]
A nice ko for Black

lavalyn Black can make a ko in which he captures first.


[Diagram]
B1 is already at the vital point

Attempts to defend the threatened corner stone do not work. (White dies in gote.)


[Diagram]
White loses

The squeeze does not work, because of shortage of liberties.

A nice one-sided ko (picnic ko) if there ever was one.



Bill: A picnic ko? That is certainly questionable. If White wins, he lives; if Black wins he dies. What is lopsided about that?
Perhaps White invaded Black's corner and managed to make ko. That kind of thing is not unusual. It is a mistake to think of something as your territory unless your opponent cannot invade to no effect.


unkx80: This solution is perfect. I'll just add a bit more. =)

Actually this one is also a kind of bent four in the corner.

[Diagram]
When Black wins the ko

If Black wins the ko, he will connect at B1. The white group becomes a bent three big eye and dies.

RexWalters: This is especially important if White has one more liberty (say the BC is missing). In this case the squeeze play above does give White life.


[Diagram]
Failure

B1 is at the wrong point; W2 lives.


[Diagram]
If White wins the ko

Of course, Black still has to win the ko fight, or it was all for nothing ...



[Diagram]
White loses?

B1 and B3 die, is that group not alive?

SAS: What group? B5 captures all White's stones...



[Diagram]
White escape?

artChimera: Sorry, but what if White plays W4 at B5 (referencing the above diagram)? Then, as I've tried to diagram here, B5 is necessary to block. Also, Black can't play in the corner without putting himself in atari. Then W6 removes B3. Black's invasion is dead on the next white move and the space has two eyes. I am really new to the game, so it's likely I'm missing something.

Andre Engels: If White plays W4 here, and Black answers at B5 (it depends on the position to the upper left whether answering is necessary), what has actually occurred is that White has played a ko threat. After White captures at W6, Black will try to find a ko threat himself. The situation is still ko: we have just had the first ko threat exchange.

Some more explanation: You want to have White capture on the next move, but what if Black plays a move which is some huge threat? Perhaps White has to answer it, and then Black can recapture at B3. White may not play immediately at W6 while Black threatens to capture at a; but maybe White finds another big threat, plays it, has it answered by Black, and then recaptures at W6. Etcetera until someone decides not to answer the opponent's threat. That's how a ko fight works.





This is a copy of the living page "Beginner Exercise 5 Solution" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.