Hi,
i have a Tsumego where I believe the best answer is a seki, but I'm wondering if the resulting position could be considered alive in some rulesets.

Click Here To Show Diagram Code

[go]$$c Black to play
$$ --------------------
$$ . . . . O X . . O . |
$$ . . . . O X X . O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

My best solution:

Click Here To Show Diagram Code

[go]$$c Seki or black alive?
$$ --------------------
$$ . . . . O X . 2 O . |
$$ . . . . O X X 1 O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

I suppose it is a seki: black has one eye, the other one contains white stones. Black can't approach white from either side without having half of his group captured. On the other hand white can't play without being captured and rendering black definitively alive.

I'm wondering if there are (official, tournament) rulesets where white is considered captured. Maybe all of them ?

Thanks

It's a seki, so they are both alive. at would be a ko if Black is feeling brave and has oodles of awesome ko threats, but generally this will just finish as seki.

Thanks, so at least my analysis was ok.

I still have the bad habit of using the word "alive" for "alive with points" only, excluding seki. Which of course is wrong, but I suppose it is a bad habit of most beginners.

Don't even start about ko , the missing ability to evaluate a situation (including potential ko threats) is a big problem. Well, I'm on tsumego for a reason.

Here is the solution with Black to play:

Click Here To Show Diagram Code

[go]$$c Black to play
$$ --------------------
$$ . . . . O X . . O . |
$$ . . . . O X X 1 O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

That's it. Black is alive. Whether White makes seki later or whether Black kills White is small.

I actually think that this is a better problem with White to play:

Click Here To Show Diagram Code

[go]$$Wc White to play
$$ --------------------
$$ . . . . O X . 3 W 1 |
$$ . . . . O X X a O X |
$$ . . . . O O X 2 X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

Black is dead because White can later play at "a" and if Black captures, White can kill on the marked point.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I forgot: the problem came from the Korean Go Academy on Gobase http://gobase.org/studying/problems/academy/?lev=2&off=20 (subscription needed).
It is in a whole bunch of tsumego where I think seki is the best solution.

Thanks again guys.

Seki is not the best solution. That would make Black live in sente.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

So white can have either seki in gote, or take sente. In that case black can get 7 points in gote, so until that moment the position is worth 3.5 points.
Is this correct?

No it is

White can kill
Black can live

and they are both in gote, (the opponent doesn't need to answer, it is lost for him anyway )

but a complication that after black has played. it is white's turn and White can choose to make it a seki (and that is again in gote)


In points:
If white plays he wins around 30 points.
If black plays we imagine he gets the seki (because that ends in white's gote)

Bill can explain it all in much more precise terms (which i hardly understand)

_________________
Promotor and Librarian of Sensei's Library

hman is right that the white followup to make seki is worth 3.5 points: (7-0)/2 = 3.5, or 3 points if you count the eye as a point (7-1)/2 = 3.

By my count if white kills it becomes -22, so the temperature for the whole thing is (3.5+22)/2 = 12.75 points for the first move to live or kill, or 13 points if you count the eye.

By Japanese and Korean scoring:

Click Here To Show Diagram Code

[go]$$c -9.25 points
$$ --------------------
$$ . . . . O X . . O . |
$$ . . . . O X X . O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

The original position is worth 9.25 points for White (White scores are negative by convention).

Click Here To Show Diagram Code

[go]$$c -22 points
$$ --------------------
$$ . . . . O X . O O O |
$$ . . . . O X X . O X |
$$ . . . . O O X X X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

If White kills the local score is 22 points for White.

Click Here To Show Diagram Code

[go]$$c 3.5 points
$$ --------------------
$$ . . . . O X . . O . |
$$ . . . . O X X X O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

If Black lives, the position is worth 3.5 points for Black. (Which is what I think you mean. )

Click Here To Show Diagram Code

[go]$$c 7 points
$$ --------------------
$$ . . . . O X . X O . |
$$ . . . . O X X X O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

If Black kills, the local score is 7 points for Black.

Click Here To Show Diagram Code

[go]$$c seki
$$ --------------------
$$ . . . . O X . O O . |
$$ . . . . O X X X O X |
$$ . . . . O O X . X X |
$$ , . . . . . O X X O |
$$ . . . . . . O O O O |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]

If White makes seki, the local score is 0. (By AGA rules it is 1 point for Black, which has to be figured into the other values. )

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Thanks everybody
I think I understood all of this.
I also think I'll be able to (start) to think like this in tsumego. In game... well I'll start trying