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i don't understand this opening choice?
http://prod.lifein19x19.com/viewtopic.php?f=11&t=8846
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Author:  cherryhill [ Wed Jul 31, 2013 11:38 pm ]
Post subject:  i don't understand this opening choice?

this is the board for the question posed:

Click Here To Show Diagram Code
[go]$$c This is a label for the diagram.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . B . P . # . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X. . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . X . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . O . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


black square and circle are options. white x is not there yet.

so black to play and the answer is circle. there is not much explanation given besides that it is more efficient, it attacks white and that square is too slow. but i don't understand it, because i know if i were to play this move on tygem, i would get attacked with white X which i don't know how to respond to.

if i respond with the same kind of pincer, i can't play my way through escaping or surviving the attack especially as there is no ladder breaker on the board for the ladders i run into

if i run, then white uses it's attacking stone to jump two spaces down the side and makes a base. which was partially the reason given for black square being too slow as white could extend the corner with a low two space jump. and when i compare the running variation with the move considered too slow, it looks like black gains a lot more territory than white in the exchange that is considered too slow

so i have to believe i'm supposed to fight off whites attack rather than run. but i dunno, i am struggling to see how its a better move.

i do get that it attacks white. i just don't see how it's practical or holds up against an attack which i have to assume is coming (especially at my level) otherwise black will strongly develop the top.

Author:  EdLee [ Thu Aug 01, 2013 12:08 am ]
Post subject: 

cherryhill, your diagram has an extra period. Without it, it would look like this:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . 1 . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . X . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . O . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ -----------------------------------------[/go]
- Where did you get this question?
- Was it a whole board problem ? Was this the entire board ?

If :w2:, B can fight with W -- a possible continuation:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . a . . . . . . . . . . . . . . |
$$ | . . . O . 1 . 2 . . 4 . 5 . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . b . . . 3 . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . X . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . O . O . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ -----------------------------------------[/go]
Sente moves like (a) and (b) can help B in the fight.

But it's important to have the whole board situation.
It's very tricky to discuss this with only a partial board like this.

Author:  Splatted [ Thu Aug 01, 2013 2:58 am ]
Post subject:  Re: i don't understand this opening choice?

I think in this it's less to do with territory and more to do with the strength of each player's groups. Look at this diagram. White has one strong and black has two weak ones, so though it's black's turn he will be on the defensive for a while:

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


Compare that to the continuation Ed Lee showed and the situation is reversed; black's two weak groups have become one strong one, and now white has two weak groups:

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

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