Here is a picture (if I can get the tags right!)



How can black attack white here or get any kind of seki?

Thanks!

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Black cannot do anything, but White cannot either. So, both sides' stones are alive: the white group, and the black group that consists of two stones in the corner (the outside black stones are assumed to live anyway, even though the cuts there should be protected in order not to distract from the problem at hand).

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A good system naturally covers all corner cases without further effort.

If white plays B18 trying to kill blacks two stones it is self atari. B can't kill white either. So we have a seki.
Technically w could cut at C14 and then kill some black stones and live without seki. But as Harleqin said that's probably outside of the problem.

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Sanity is for the weak.

Wow, thanks for the help! But I still don't understand!

Why isn't A16 a second eye for the white group, so that white can live no matter what happens in the corner?

I didn't realize just how much of a beginner I am!

Thanks!

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A16 is an eye. But B18 is no eye, just a shared liberty between the black and white stones.
White can't capture the two black stones in the corner. But can't be captures either. Because playing on the shared liberty at B18 would be suicide for both sides.

_________________
Sanity is for the weak.

A16 is white's first and only eye. A seki is a situation where neither player can kill the other without getting to play more than once in a row. In your example, if either player plays A19 (which white can't, anyways), B18, or A16, they are in atari. Even though black is outnumbered in the area, his two stones have as many liberties as all of the white ones. There are three ways that this could be resolved. First, it could remain seki forever, scoring no points for either. Second, either player could play something like B18 as a ko threat, in which case one player would get to kill the other here. Lastly, if white managed to kill some of the outside stones, like B14, white would have enough liberties to kill the two internal black stones.

Essentially, an eye doesn't count as an eye if there are opposing stones inside that you can't kill.

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Someday I want to be strong enough to earn KGS[-].

Ah, not suicide, but self-atari. Wow. Now I see. That space at A16 would be the white group's only remaining liberty.

So a real eye is just one empty space, which prevents any such funny business by black.

I sure have a lot to learn!

Thanks!

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That's the key. This seki stuff is something I am just learning about. I didn't realize how "interesting" it can get!

Thanks so much for all the help!

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Not exactly. In this case, the black group simply forms an eye in the corner (yes, it is an eye, because White cannot approach at B18!), and the white group forms an eye at A16. So, these are two groups with one eye each, facing off at B18.

It is important to understand that both groups are alive.

_________________
A good system naturally covers all corner cases without further effort.

cannot white cut ?

Click Here To Show Diagram Code

[go]$$B Corner
$$ ------------------
$$ | . X O X . . . . .
$$ | X . O X . . . . .
$$ | O O O X . . . . .
$$ | . O X . 5 . . . .
$$ | O O X . . . . . .
$$ | X X 2 4 . . . . .
$$ | . 6 3 . . . . . .
$$ | 8 7 . . . . . . .
$$ | . . . . . . . . .[/go]

_________________
长考出臭棋.

Click Here To Show Diagram Code

[go]$$B Corner
$$ ------------------
$$ | . X O X . . . . .
$$ | X . O X . . . . .
$$ | O O O X . . . . .
$$ | . O X . . . . . .
$$ | O O X . . . . . .
$$ | X X 2 . . . . . .
$$ | . 3 . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

I don't know if this is better, but the atari obviously is bad for black. He can't afford to prioritize one over the other.

More importantly, in this sort of corner problem, I think it is generally asssumed that the outside are stable and connected out. So we just assume that there are more stones on the board than we can see, and that those stones connect to nullify issues like that.

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Someday I want to be strong enough to earn KGS[-].

I'm sorry - this really reveals my incompetence! Shotwell's book did not have that gap in the black stones! I didn't think it mattered! Wow! No wonder I lose almost every game I play!

To test my understanding - I have created a similar pattern but out away from the edge. Is this also a seki? Whoever plays at L10 puts themselves into atari - correct?

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It risks a ladder?

Click Here To Show Diagram Code

[go]$$B Corner
$$ ------------------
$$ | . X O X . . . . .
$$ | X . O X . . . . .
$$ | O O O X . . . . .
$$ | . O X 4 . . . . .
$$ | O O X . . . . . .
$$ | X X 2 . . . . . .
$$ | . 3 . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

Wow, that go tag is nifty!

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Oh, never mind! I can't think more than one move ahead!

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Great job! You have a lot better understanding of seki than I did at your level. =D

As far as the ladder thing, yeah, there would be fighting and such. I didn't even bother reading if there was a way to live for sure. Like I said, often corner problems will have unclear boundaries that we just have to take for granted, so I assumed it was just meant that way.

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Someday I want to be strong enough to earn KGS[-].

This is a good idea actually:

Click Here To Show Diagram Code

[go]$$B Corner
$$ ------------------
$$ | . X O X . . . . .
$$ | X . O X . . . . .
$$ | O O O X 7 . . . .
$$ | . O X 4 6 . . . .
$$ | O O X 5 8 . . . .
$$ | X X 2 9 . . . . .
$$ | . 3 0 . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code

[go]$$Bm11 Corner
$$ ------------------
$$ | . X O X . . . . .
$$ | X . O X . . . . .
$$ | O O O X X . . . .
$$ | . O X O O . . . .
$$ | O O X X O . . . .
$$ | X X O X . . . . .
$$ | . X O 2 . . . . .
$$ | . 1 . . . . . . .
$$ | . . . . . . . . .[/go]

Ladder!

How did you get 11 and 12? I look at the code, it's still 1 and 2.

_________________
长考出臭棋.

It has $$Bm11 in the header. m11 says it starts with move 11. Check the diagram manual.

_________________
Sanity is for the weak.

Yes.

_________________
A good system naturally covers all corner cases without further effort.

Ha, thanks.

How about this, kukula

Click Here To Show Diagram Code

[go]$$
$$ ------------------
$$ . . O O X X O O .
$$ . . O X . . X O .
$$ . . O X . . X O .
$$ . . O X O O X O .
$$ . . O X X X X O .
$$ . . O O O O O O .
$$ . . . . . . . . .
$$ . . . . . . . . .
$$ . . . . . . . . .[/go]

_________________
长考出臭棋.