PillboxThePlayer/EyeSpacesQuestions

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Table of contents Table of diagrams
White definitely alive?
maybe...
Yes, seems to lead to forced seki for B.
White can block...
White definitely alive?
Omitting , one outside liberty


Shape from a game on 2008-03-12

This is a shape that came up during a game I was playing (poorly) and won.

My opponent resigned, and then asked to play out the game anyway. The Score Randomizer during the review indicated B+3.5, and I didn't pay much attention to it. I figured I had lost and was lucky that my opponent only resigned because of a failed invasion.

Later, after reviewing the game, I checked the Score Randomizer again and it considered this corner dead. Which was contrary to my initial reading.

[Diagram]

White definitely alive?

[Diagram]

maybe...

pillbox: thoughts?

[Diagram]

Yes, B1 seems to lead to forced seki for B.

This leads to the position in IsThisSekiInTheCorner. Any different response looks worse for W. Note that W next at 1-1 starts an infinite cycle of "W 1-1, B take, W take, B pass". -- ChrisBall.

Karl Knechtel: See also sending two returning one.

[Diagram]

White can block...

pillbox: Looks like W can block at a, b, or c to force life.


[Diagram]

White definitely alive?

LukeNine45: With two outside liberties, white can play a and is alive. With only one, W4 is a ko threat to live outright, but black can fill an outside liberty to keep it seki. With no outside liberties, white omits W4 and it is a gote seki for black. (Later: The rest of this paragraph is completely wrong:) Note that this W2 is better than the one in the above diagrams, because here white can omit W4. Above, if white does so, black can make a ko.


Karl Knechtel: Er, Black can still make a ko if White omits W4 in the "improved" line (unless there are two outside liberties, in which case White can play oshitsubushi)...

[Diagram]

Omitting W4, one outside liberty

A Black capture at b would either leave a dead bulky five inside, or allow Black to capture by me ari me nashi, and White at b is dead in gote, so White must play a, and Black takes first in the resulting ko.

LukeNine45: Yes, I don't know what I was thinking.


This is a copy of the living page "PillboxThePlayer/EyeSpacesQuestions" at Sensei's Library.
(OC) 2008 the Authors, published under the OpenContent License V1.0.
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