Move 12 by my opponent: http://eidogo.com/#klU95P1:0,12

is threatening to seal me in the corner. I have come up with numerous responses besides the game response. I would appreciate any feedback on how to think about his play threatening to seal me in my corner.

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I don't think you have to worry about getting sealed in the corner. You can always jump out, even if he plays on the bottom side.

However, when you indicate concern of being sealed in the corner, it is interesting to me that you did not play 25 @ M3.

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Your corner looks capable even if sealed in. If w approaches from N3, I'd probably just pincer the approach and figure the corner can make its own life.

Click Here To Show Diagram Code

[go]$$W Something like this?
$$ . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . |
$$ . . . . . . . . 6 . O . . |
$$ . . . . . . 3 . . . . . . |
$$ . . . , . . 5 4 . , X . . |
$$ . . . . 2 . 1 . X . . . . |
$$ . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . |
$$ --------------------------+[/go]

I think both and the previous W approach are too close to your corner enclosure.

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Keep in mind, I am frequently wrong.

No, his is not threatening anything and is gote. You can tenuki.
aurik's variation strengthens W and hurts :

Click Here To Show Diagram Code

[go]$$W
$$. . . . . . . . . . . |
$$. . . . . . . . . . . |
$$. . . . . . . . . . . |
$$. . . . . . 6 . O . . |
$$. . . . 3 . . . . . . |
$$. , . . 5 4 . , X . . |
$$. . 2 . 1 . X . . . . |
$$. . . . . . . . . . . |
$$. . . . . . . . . . . |
$$----------------------+[/go]

Simply jump out, then (a) and (b) directions are miai for you:

Click Here To Show Diagram Code

[go]$$W
$$. . . . . . . . . . . |
$$. . . . . . . . b . . |
$$. . . . . . . . . . . |
$$. . . . . . . . O . . |
$$. . . . . . 2 . . . . |
$$. , . . . . . , B . . |
$$. a . . 1 . B . . . . |
$$. . . . . . . . . . . |
$$. . . . . . . . . . . |
$$----------------------+[/go]

You need to play that shimari many times to understand its meanings.

maybe the question arise from a definition issue: (what is the definition police doing ?)

a sealed corner is a corner blocked on either side, AND with no access to the center. This i not good.

a corner which cannot extends to either side BUT is alive and can go in the center is usually fine, hence Ed lees variation to just get out after W approach form the other side (here W @ would indeed seal B ).
Edit: well maybe here B can get out after W @ but thats not the point

in other words to properly seal you W needs at least 2 moves and not just 1 on the side so you can tenuki form the corner now

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