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What are the disadvantages of this corner sequence?
http://www.lifein19x19.com/viewtopic.php?f=15&t=11954		 Page 1 of 1
Author:  Celebrir_ [ Wed Jun 17, 2015 10:06 am ]
Post subject:  What are the disadvantages of this corner sequence?
Today I encountered a very weird joseki I don't know the disadvantages of and I hope you can help me.

Click Here To Show Diagram Code
[go]$$c joseki dictionaries say that 5 should be at a, b or c
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . 1 . a b . d .
$$ | . . . , 5 . 7 . . ,
$$ | . . c 2 6 4 . . . .
$$ | . . . . . . . . . .
$$ | . . . 3 . . . . . .
$$ | . . . . . . . . . .[/go]


Can W come from d without caring to much about his group? That seems very dangerous.
I felt horrible in the actual game:

Click Here To Show Diagram Code
[go]$$W joseki dictionaries say that 5 should be at a, b or c
$$ ---------------------
$$ | . . . . . . . . . .
$$ | . . 2 . . . . . . .
$$ | . . 1 X 4 . . . . .
$$ | . . a 3 X . X 6 . ,
$$ | . . . O O O 5 . . .
$$ | . . . . . . . . . .
$$ | . . . X . 8 . . . .
$$ | . . . . . . . . . .
$$ | . . . 7 . . . . . .[/go]

I was thinking about 7 at 8 but it seemed to good to give B another natural move at the left side. Besides 3 should have been at a I guess.
Author:  HermanHiddema [ Wed Jun 17, 2015 11:24 am ]
Post subject:  Re: What are the disadvantages of this corner sequence?
I'd look at pushing and cutting:

Click Here To Show Diagram Code
[go]$$Wc19
$$ +--------------------
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . X . 2 3 . . .
$$ | . . . , X 1 X . . ,
$$ | . . . O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . X . . . . . .
$$ | . . . . . . . . . .[/go]


Now, how does black continue? Some options:

Click Here To Show Diagram Code
[go]$$Bc19m4
$$ +--------------------
$$ | . . . . . . . . . .
$$ | . . . 7 6 2 . . . .
$$ | . . . X 3 X O 4 8 .
$$ | . . 0 , X O X 1 5 9
$$ | . . . O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . X . . . . . .
$$ | . . . . . . . . . .[/go]


Extending from the cut doesn't look good

Click Here To Show Diagram Code
[go]$$Bc19m4
$$ +--------------------
$$ | . . . . . . . . . .
$$ | . . . . . 4 2 3 . .
$$ | . . . X 5 X O 1 . .
$$ | . . . , X O X 6 0 ,
$$ | . . . O O O 7 9 . .
$$ | . . . . . . 8 . a .
$$ | . . . X . . . . . .
$$ | . . . . . . . . . .[/go]


If the ladder is good for white, this looks disastrus for black. Otherwise, he can capture the three stones, but white can play a and seal black in.

Click Here To Show Diagram Code
[go]$$Bc19m4
$$ +--------------------
$$ | . . . . . . . . . .
$$ | . . 5 8 6 . 2 . . .
$$ | . 0 4 X 7 X O 1 . .
$$ | . . 9 , X O X 3 . ,
$$ | . . . O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . X . . . . . .
$$ | . . . . . . . . . .[/go]


Protecting the cut prevents the ladder/geta, but leaves options in the corner. Certainly :b8: is unplayable now, so white can take the corner.
Author:  HermanHiddema [ Thu Jun 18, 2015 12:26 am ]
Post subject:  Re: What are the disadvantages of this corner sequence?
Just a small additional remark. White should probably attach in the corner first. It has no disadvantages and limits black's options later, so it feels like the proper order of play.

So like this:

Click Here To Show Diagram Code
[go]$$Wc19
$$ +--------------------
$$ | . . . . . . . . . .
$$ | . . 2 . . . . . . .
$$ | . . 1 X . 4 5 . . .
$$ | . . . , X 3 X . . ,
$$ | . . . O O O . . . .
$$ | . . . . . . . . . .
$$ | . . . X . . . . . .
$$ | . . . . . . . . . .[/go]
Author:  Uberdude [ Thu Jun 18, 2015 5:03 am ]
Post subject:  Re: What are the disadvantages of this corner sequence?
Though it's worth noting that playing the corner attach first does give black the option to realise his impending doom and compromise with something like this, though white is of course happy to take the corner and eye black's shape weaknesses like a (though that might activate his own weakness at b) or attacking the whole thing at c.

Click Here To Show Diagram Code
[go]$$Wc19
$$ +--------------------
$$ | . . . . . . . . . . .
$$ | . . 5 3 4 . . . . . .
$$ | . . 1 X . a . . 2 . c
$$ | . . b , X . X . . , .
$$ | . . . O O O . . . . .
$$ | . . . . . . . . . . .
$$ | . . . X . . . . . . .
$$ | . . . . . . . . . . .[/go]


There are actually some shapes like this where it is best to not answer the corner attach, for example in the game below 29 should probably be at L4 and let me take the corner in gote and then help the 3 stones (and my 30 could be aji keshi too as I can p2).
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