Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . X . . . X . . X . O . . . . |
$$ | . . . O . . . X . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . O . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , O . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . O . O , X . . |
$$ | . . . X . O . . O . . . . O X X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

This position is from a game between two 3kyu's reviewed by a 3d on GTL, black has just extended to q14 and white then plays at o15 but asks if maybe s18 would be better direction where the reviewer say's "this corner cannot be invaded, so you shouldn't make a slow, small move like o15 now." This was the first time I've heard a strong player say that that shape in the upper right corner is impenetrable. Seems like a lot of space for a corner; is there really nothing black can do here - friends on both sides? Cute little ko maybe?

_________________
"Tsumegos are for reading power and Tesujis for knowing which moves to read"

The corner may be safe but it can be sealed in so I see nothing wrong with moving out. But O15 can be cut (Q15 then O16) so I think I would prefer to move out with N16.

Having said that, I don't think it is urgent to move out right away, but I do think that W needs to be sure to have sente when the time is right.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

If white wants to come out, it probably would have been better to play this way (I'm assuming r15 q14 were the last 2 moves).

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . X . . . X . . X . O . . . . |
$$ | . . . O . . . X . , . . . . . O 6 . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . O . . . . . . . . . . 4 2 1 . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . a b . . |
$$ | . . O , O . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . c . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . O . O , X . . |
$$ | . . . X . O . . O . . . . O X X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

If would be sensible for black to add a move on the right to prevent a white attack at a/b, but then a white jump around c would nicely expand white's lower side framework and make black upset to defend the not so big and rather overconcentrated territory on the right.

As for the original question, are you sure it was this corner (http://senseis.xmp.net/?ThreeCrows) they were talking about, which does happen every so often but the rather more common shape is the below which does have a much bigger problem at 3-3.

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . X . . . X . X . O . . . . . |
$$ | . . . O . . . X . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . O . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , O . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . O . O , X . . |
$$ | . . . X . O . . O . . . . O X X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Thank you for confirmation, and interesting insights.



Three Crows? Yeps. Thanks for the link. Is there an index of english shape/pattern names somewhere? Didn't really see anything comprehensive on Sensei's. Correct assumption at the last two moves btw.

_________________
"Tsumegos are for reading power and Tesujis for knowing which moves to read"

Do you know about the SL postition search?

http://senseis.xmp.net/?positionsearch=1

In this case searching for those 3 stones would take you directly to the SL Three Crows page. It's a great tool.

Didn't know about this feature, thanks a bunch!

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"Tsumegos are for reading power and Tesujis for knowing which moves to read"