Tsumego From Games 55 / Solution

Sub-page of TsumegoFromGames55
[Diagram]

corner

This also lives.

Dieter: Yes, but with less points. The question concerned the status of the White group if White plays elsewhere.

ilan: The Oracle of ilan answered your original question and will now move on.

Dieter: Maybe someone else wants to try if the group could live without White answering locally.


[Diagram]

My attempt

Grauniad: I don't see how White can live after a Black move at the same point.

[Diagram]

Answer

B9 prevents ko and makes miai of a and b. This and move B5 are not obvious to me, and I suspect there may be holes in the reasoning.

[Diagram]

Different Answer

Ed?: White is alive here at 'a' or 'b'.

[Diagram]

Different Answer


[Diagram]

ko

ed?: B3 here threatens to separate the the white stones by pushing through at W4. If the exchange of W8 for B9 is not sente then black can kill.

[Diagram]

ko

White throws in with W3 to make a ko. White will play at either point 'a' to finish the ko.

[Diagram]

Alternative for black 7

White is alive here.

[Diagram]

Alternative for black 5

White is alive after W2


[Diagram]

Increasing eye space

If the exchange of W8 for B9 is not sente for white black can kill.

[Diagram]

approach ko

Black can get a sente seki by exchanging 'a' for 'b'. Playing 'c' instead leaves open the possibility of a ko. White 'b' in response to 'c' leaves a 1000 yr ko, although if white starts it early by throwing in at 'a' it is a direct ko for white but black will need a lot of approach moves. If black can play 'c' and white tenuki's, black 'b' makes it a direct ko.

This diagram seems to be white's best option.


[Diagram]

Playing underneath 1

Here white dies. W3 at B4 would give ko after black pushes through at W3.

[Diagram]

Playing underneath 2

'a' and 'b' are miai so white must fight the ko


[Diagram]

Not clever

Resisting with W2 is clearly bad, white collapses.


[Diagram]

Seki

This attack leads to seki. W6 at 'a' would lead to ko. Again white is dead if the exchange of W8 for B9 isn't sente.

[Diagram]

Seki

If B2 at W3 then white lives with territory at 2.

(Hicham): Isn't 4 atari?

Ed? True white needs to exchange 'a' for 'b' before playing B5


[Diagram]

corner

[alternative: alive --Dieter


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