This corner position arose in a game yesterday between me and a friend (both double digit kyu). The rest of the board is fairly full, and white's surrounding stones are fully alive.

In our game we both had evaluated black as alive and were ignoring the position, (but I think we may have been wrong). When my friend invaded during a ko fight as a ko threat, I re-evaluated and decided I was in big trouble here, and decided to give it up and win the ko fight as compensation, since it was fairly large, and winning it was almost as valuable as this corner.

What is the status of the corner group? Thanks!

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[go]$$c What is the status of this corner group?
$$ ---------------------------------------
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . . X O O . . . . . . . . . . . . . |
$$ | X X . X X O . . . . . . . . . . . . . |
$$ | X X X O O O . . . , . . . . . , . . . |
$$ | O O O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

If black plays first, it's alive:

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

If white plays first, it's either ko or seki, depending on white:

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[go]$$Wc Seki
$$ ---------------------------------------
$$ | . 3 . X O . . . . . . . . . . . . . . |
$$ | 2 1 4 X O O . . . . . . . . . . . . . |
$$ | X X . X X O . . . . . . . . . . . . . |
$$ | X X X O O O . . . , . . . . . , . . . |
$$ | O O O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Wc Ko
$$ ---------------------------------------
$$ | . 4 3 X O . . . . . . . . . . . . . . |
$$ | 2 1 . X O O . . . . . . . . . . . . . |
$$ | X X . X X O . . . . . . . . . . . . . |
$$ | X X X O O O . . . , . . . . . , . . . |
$$ | O O O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

_________________
be immersed

Thanks!

I literally just looked at this problem in maeda intermediate tsumego! It's problem number 52

Nice.

It had seemed to me that it was just barely large enough to live, and thus wasnt worth a move. But when he invaded on the 2-2 space I realized that the lack of connection between the groups was a problem.