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Pressured corner : is it alive ?
http://www.lifein19x19.com/viewtopic.php?f=15&t=4105		 Page 1 of 1
Author:  Tryphon [ Thu Jun 23, 2011 3:30 pm ]
Post subject:  Pressured corner : is it alive ?
I encountered this position in a handicap game : after 6, both my opponent and me thought Black live in the corner, and he tenukied. I thought it was still alive so I didn't play there until the endgame, where I played 8 to reduce the corner.

To my surprise, I actually killed him. Did he make a mistake or was it unavoidable ?

Since I am to it, is 6 the proper move ?

Click Here To Show Diagram Code
[go]$$B
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . . 8 . . . |
$$ . . . . 4 . . 5 . . |
$$ , . . . . . 1 . . . |
$$ . . . . . 6 . . . . |
$$ . . . . . . . 2 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


:b3: :b7: tenuki.
Author:  Bill Spight [ Thu Jun 23, 2011 4:12 pm ]
Post subject:  Re: Pressured corner : is it alive ?
Black can live.

Click Here To Show Diagram Code
[go]$$B Joseki
$$ --------------------
$$ . . . . . . . . . . |
$$ . . . . . . 8 . . . |
$$ . . . . 4 . . 7 . . |
$$ , . . . . . 1 . . . |
$$ . . . . . 6 . . . . |
$$ . . . . . . . 2 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


:b3:, :b5: elsewhere.

This is usually how this position arises. Your :w6: was fine.

Click Here To Show Diagram Code
[go]$$B Joseki
$$ --------------------
$$ . . . . . . 9 . . . |
$$ . . . 0 . . O 1 . . |
$$ . . . . O . 2 X . . |
$$ , . . . 8 7 X 5 . . |
$$ . . . . . O . 4 3 . |
$$ . . . . . . . O 6 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


:b7: and :b9: are tesuji.

Click Here To Show Diagram Code
[go]$$Bm11 Joseki (continued)
$$ --------------------
$$ . . . . . . X . . . |
$$ . . . O . . O X . . |
$$ . . . . O . O X . . |
$$ , . . . O X X X . 1 |
$$ . . . . . O . O X . |
$$ . . . . . . . O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


Now to show that Black is alive.

Click Here To Show Diagram Code
[go]$$W Life
$$ --------------------
$$ . . . . . 5 B 1 6 . |
$$ . . . O . . O X 2 . |
$$ . . . . O . O X . 4 |
$$ , . . . O X X X . X |
$$ . . . . . O . O X . |
$$ . . . . . . . O O 3 |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


:b2: is tesuji. If you missed it, join the club. ;)

You see the importance of :bc:.

Click Here To Show Diagram Code
[go]$$W Death
$$ --------------------
$$ . . . . . . X 1 2 . |
$$ . . . O . . O X 6 3 |
$$ . . . . O . O X . 4 |
$$ , . . . O X X X 7 X |
$$ . . . . . O . O X . |
$$ . . . . . . . O O 5 |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


:b2: is a mistake, which allows the tesuji of :w3:.

Very clever of Black to live, eh? :)
Author:  Tryphon [ Fri Jun 24, 2011 12:33 am ]
Post subject:  Re: Pressured corner : is it alive ?
Tricky...

Thanks a lot, I turned around and didn't see that at all.

I wouldn't have missed the tesuji at 2 in your before-the-last diagram, but I totally missed the two before :mrgreen: (I had to put the stone to understand why they were tesuji).

We should have a "venerate" button for the likes of you :bow:
Author:  perceval [ Fri Jun 24, 2011 12:41 am ]
Post subject:  Re: Pressured corner : is it alive ?
interesting, this position is known and dismissed as small life for Black, but they should put in huge red letters that you need to solve dan level tsumego to get this small life (i say dan level i am not sure but clearly those 3 tesuji almost in a row are several stones above me).
Author:  tj86430 [ Fri Jun 24, 2011 12:55 am ]
Post subject:  Re: Pressured corner : is it alive ?
Totally OT, but why is this white:

Click Here To Show Diagram Code
[go]$$B Joseki
$$ --------------------
$$ . . . . . . X . . . |
$$ . . . W a . O X . . |
$$ . . . . O . O X . . |
$$ , . . . O X X X . . |
$$ . . . . . O . O X . |
$$ . . . . . . . O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]

better than a?
Author:  EdLee [ Fri Jun 24, 2011 1:27 am ]
Post subject: 
perceval wrote:
you need to solve dan level tsumego to get this small life
B tenuki twice; what did you expect -- for B to play 20k moves and live in sente? :P
Author:  hyperpape [ Fri Jun 24, 2011 3:17 am ]
Post subject:  Re: Pressured corner : is it alive ?
That's true of more corner positions than you know, Perceval. Every so often, the right variation comes up and you or I will just die with a "live" group.
Author:  gogameguru [ Fri Jun 24, 2011 3:36 am ]
Post subject:  Re: Pressured corner : is it alive ?
tj86430 wrote:
Totally OT, but why is this white:

Click Here To Show Diagram Code
[go]$$B Joseki
$$ --------------------
$$ . . . . . . X . . . |
$$ . . . W a . O X . . |
$$ . . . . O . O X . . |
$$ , . . . O X X X . . |
$$ . . . . . O . O X . |
$$ . . . . . . . O O . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]

better than a?


To answer a question with a question, which move gives white more influence over the top side of the board? And is white making any territory towards the top right corner?

Here's a similar variation to help you think about the marked stone:

Click Here To Show Diagram Code
[go]$$Bm11 Black 11 changes little
$$ --------------------
$$ . . . . 8 1 X 4 9 . |
$$ . . . W . 2 O X 5 . |
$$ . . . . O . O X . 7 |
$$ , . . . O X X X . 3 |
$$ . . . . . O . O X . |
$$ . . . . . . . O O 6 |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |[/go]


Also, in typical Bill style, he has taught you a strong endgame sequence without telling you :).

David
Author:  Bill Spight [ Fri Jun 24, 2011 6:44 am ]
Post subject:  Re: Pressured corner : is it alive ?
Tryphon wrote:
Tricky...

Thanks a lot, I turned around and didn't see that at all.

I wouldn't have missed the tesuji at 2 in your before-the-last diagram, but I totally missed the two before :mrgreen: (I had to put the stone to understand why they were tesuji).


Well, I learned this joseki when I was 4 kyu, and I was clueless about the whole thing. ;)

Quote:
We should have a "venerate" button for the likes of you :bow:


Well, thank you. :) And I see that a lot of people liked the post.

Just reporting what's in the book, folks. :-|
Author:  SoDesuNe [ Fri Jun 24, 2011 1:10 pm ]
Post subject:  Re: Pressured corner : is it alive ?
Bill Spight wrote:
Just reporting what's in the book, folks. :-|


That's the true sadness of our time. We have everything written down somewhere in books, but only few know the right time to reveal the wisdom from the right book ; )
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