I took a short nap after work today and had a go dream. In the dream there was a weird kind of seki based on a particular kind of snapback. It was a seki because black had one eye couldn't capture the two stones in the snapback because white could throw in and make the eye false. But white couldn't play into the snapback either because it would become a case of "capture three to get an eye" making black live. If that makes any sense.

I tried to construct a similar position after I woke up, but it's tricky. I'm not sure if it's possible, but I'm not sure it's impossible, and I'll never sleep again until I know.

Click Here To Show Diagram Code

[go]$$B Not quite a seki
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , X X X X . , . . . . . , . . . |
$$ | . . . . X O O X X . . . . . . . . . . |
$$ | . . . . X O . O X . . . . . . . . . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . O . O X O . X O O O O O X X X X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . . O X X . O O X X . X . O . O X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . O . O X O . X O O O O O X X X X . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . . . . X O . O X . . . . . . . . . . |
$$ | . . . . X O O X X . . . . . . . . . . |
$$ | . . . , X X X X . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Please ignore the spaceship shape. You can see the lynch-pin white stones in the snapback in the middle there. You can see it doesn't quite work. If black captures the two stones, white could throw in to make the eye false, but black would have a spare liberty to capture one of the white wing groups. But I'm not convinced it can't be made to work as a true seki with a little adjustment. Maybe the number or shape of the white lynch-pin shapes needs to change, or maybe the white wings need to be a connected chain somehow.

Little help?

_________________
KGS 4 kyu - Game Archive - Keyboard Otaku

This sounds a little like a hanezeki

Click Here To Show Diagram Code

[go]$$B Not quite a seki
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . X X O X X . . . . . . . . . . . . |
$$ | . . X O . O X X . , . . . . . , . . . |
$$ | . . X O O O O X X . . . . . . . . . . |
$$ | . . X X X O . O X . . . . . . . . . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . O . O X O . X O O O O O X X X X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . . O X X . O O X X . X . O . O X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . O . O X O . X O O O O O X X X X . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . . X X X O . O X . . . . . . . . . . |
$$ | . . X O O O O X X . . . . . . . . . . |
$$ | . . X O . O X X . , . . . . . , . . . |
$$ | . . X X O X X . . . . . . . . . . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

This makes it into some kind of semi-awesome thousand year ko.

Now Black can't reduce the liberty without White creating a snapback, yet White can't remove the liberty because Black captures the two middle stones and then can take the game-winning ko - no ko threat will be worth it.

It's a little like a hanezeki, but in the dream it was a case of whether or not black would get a second eye (white capturing would give him one, black capturing would prevent one), instead of being an issue of the number of liberties in a capturing race.

@topazg: Would it then be a seki by default?

Now if only my dreams would produce USEFUL analysis.

_________________
KGS 4 kyu - Game Archive - Keyboard Otaku

Yeah, it was supposed to be, but ...

Nope, this doesn't work either. Black can win by capturing first then creating a double ko. If White doesn't find a threat, Black removes a liberty and the loss of the double ko loses all White middle groups.

What fun...



Of course, 4 moves in a row isn't small either

black can take ko first..then white will die

_________________
"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson

Why doesn't black just kil lthe white on the right? Take the two stones, then w throws anothero ne in, take that too, and then whatever white plays next, black can put the right into atari.

Click Here To Show Diagram Code

[go]$$B Not quite a seki
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . X X O X X . . . . . . . . . . . . |
$$ | . . X O . O X X . , . . . . . , . . . |
$$ | . . X O O O O X X . . . . . . . . . . |
$$ | . . X X X O . O X . . . . . . . . . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . O . O X O 4 X O O O O O X X X X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . . O X X 1 3 2 X X . X 5 O . O X . . |
$$ | . O O O O X X X O X X X O O O O X . . |
$$ | . O . O X O . X O O O O O X X X X . . |
$$ | . . O O X O O O X X X X X X . . . . . |
$$ | . . X X X O . O X . . . . . . . . . . |
$$ | . . X O O O O X X . . . . . . . . . . |
$$ | . . X O . O X X . , . . . . . , . . . |
$$ | . . X X O X X . . . . . . . . . . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

_________________
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My hunch is that this position, with three separate white groups, will be impossible to construct. However, I have no proof.

The main thing is what happens after black captures these two stones and white makes the throw in. Immediately the outside black group will gain a lot of liberties, so we face the following problems in position construction:
* White must prevent black from capturing the throw in stone and approaching the right white group.
* White must prevent black from approaching either the top or bottom white group.
* White may face shortage of liberties when preventing black from making any of the above two approaches.

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The trick I guess would be to make sure black doesn't get extra liberties by capturing. The reason why he gains extra right now is because two unconnected chains become connected and then share their outside liberties.

To fix that, I suppose it could start with the two black groups already connected via some outside dragon shape and with only one liberty shared with the white wing groups. But then, the two white groups would also have to be connected and have only one eye and the one shared liberty. Is that topologically possible with the black groups also connected in that way?

And that might still not work.

Stupid dreams and their stupid impossible positions.

_________________
KGS 4 kyu - Game Archive - Keyboard Otaku

OK, this still doesn't work, but it's closer I think. But it seems that black is just alive in some sort of weird not-quite two-headed dragon thing.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X X X X X X X X X X X X X . . . |
$$ | . . . X O O O O O O O O O O O X X X X |
$$ | . . . X O . O X X X X X X X O O O O X |
$$ | . O O X X O O X O O O O O X X X X O X |
$$ | O . O O O X X X O X X X O O O O X O X |
$$ | O O O X X . O O X X . X . O . O X O X |
$$ | O . O O O X X X O X X X O O O O X O X |
$$ | . O O X X O . X O O O O O X X X X O X |
$$ | . . . X O O O X X X X X X X O O O O X |
$$ | . . . X O O O O O O O O O O O X X X X |
$$ | . . . X X X X X X X X X X X X X . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

_________________
KGS 4 kyu - Game Archive - Keyboard Otaku

This is seki, white cannot capture the two black stones but black can capture the two white ones (but it stays seki if he does so).

_________________
That which can be destroyed by the truth should be.
--
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I'm afraid it doesn't look like seki to me. Black can take and kill:

oops.

_________________
That which can be destroyed by the truth should be.
--
My (sadly neglected, but not forgotten) project: http://dailyjoseki.com

None of these seem to even potentially involve black getting an eye as constructed: J9 and J11 prevent it from being "capture three to get an eye"

If you take that away, you're just trying to construct a hanezeki I guess? (That is, it's just about liberties.) I'm not sure of a local picture for "capture three to make an eye" that could be involved in a seki as you describe.