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3-4 joseki question
http://www.lifein19x19.com/viewtopic.php?f=15&t=7831
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Author:  quantumf [ Thu Feb 07, 2013 11:27 pm ]
Post subject:  3-4 joseki question

I have a question about a pretty famous variation in a 3-4 pincer joseki. I've given the full sequence for those not familiar with it.

It starts like this

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


And carries on like this

Click Here To Show Diagram Code
[go]$$Bcm11
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . a . . . |
$$ | . . . . . . . . . . . . . . . . 2 b . |
$$ | . . . , . . . . . , . X . . O O X . . |
$$ | . . . . . . . . . . . . . O X . 3 . . |
$$ | . . . . . . . . . . . . . O X . X . . |
$$ | . . . . . . . . . . . . . . 1 O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]


Generally, a is played if black has the ladder, otherwise b. Certainly b is desirable to play. Sometimes b can even be played without the ladder. Anyway, that is not really the point of this question. Let us carry on with the b line.

Click Here To Show Diagram Code
[go]$$Bcm15
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 8 7 5 9 . . . |
$$ | . . . . . . . . . . . . 4 3 6 0 O O . |
$$ | . . . , . . . . . , . X 2 1 O O X . . |
$$ | . . . . . . . . . . . . . O X . X . . |
$$ | . . . . . . . . . . . . . O X . X . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]


Now black cuts, and the variation continues

Click Here To Show Diagram Code
[go]$$Bcm25
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 2 4 O X X X . . . |
$$ | . . . . . . . . . . 3 . O X O O O O . |
$$ | . . . , . . . . . , . X O X O O X . . |
$$ | . . . . . . . . . . . . 1 O X . X . . |
$$ | . . . . . . . . . . . . . O X . X . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]


The joseki more or less ends here, and issues of ladders in opposite corner arise, or black needs to make something of the either the right or top. My question is, why does white not play 26 at 27? From what I can tell, white always plays 27 at 27, regardless of the ladder situation, so I guess I'm missing some obvious move or sequence. Would be grateful for any explanation.

The sensei's page for this is at http://senseis.xmp.net/?34PointHighAppr ... ncerOgeima

Author:  lovelove [ Thu Feb 07, 2013 11:42 pm ]
Post subject:  Re: 3-4 joseki question

Click Here To Show Diagram Code
[go]$$Wcm1
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . 2 . . . . 6 . |
$$ | . . . . . . . . . . . 3 O X X X 4 5 . |
$$ | . . . . . . . . . . 1 . O X O O O O . |
$$ | . . . , . . . . . , . X O X O O X . . |
$$ | . . . . . . . . . . . . X O X . X . . |
$$ | . . . . . . . . . . . . . O X . X . . |
$$ | . . . . . . . . . . . . . . X O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]

Famous joseki mistake. Black wins the capturing race.

Author:  HermanHiddema [ Fri Feb 08, 2013 2:22 am ]
Post subject:  Re: 3-4 joseki question

An example of: http://senseis.xmp.net/?TwoHanesGainALiberty

Author:  SoDesuNe [ Fri Feb 08, 2013 2:33 am ]
Post subject:  Re: 3-4 joseki question

quantumf wrote:
Click Here To Show Diagram Code
[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 3 . . 2 8 1 . . |
$$ | . . . . . . . . . . . . . 6 5 . . . . |
$$ | . . . . . . . . . . . . . 0 7 . 9 . . |
$$ | . . . . . . . . . . . . . . . 4 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]


Playing :w10: here is "wrong" move order. You first hane above :b1:.

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


Although this has been played - that's right - in a Korean game : D

Author:  ez4u [ Fri Feb 08, 2013 4:37 am ]
Post subject:  Re: 3-4 joseki question

SoDesuNe wrote:
quantumf wrote:
Click Here To Show Diagram Code
[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . 3 . . 2 8 1 . . |
$$ | . . . . . . . . . . . . . 6 5 . . . . |
$$ | . . . . . . . . . . . . . 0 7 . 9 . . |
$$ | . . . . . . . . . . . . . . . 4 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ +---------------------------------------+[/go]


Playing :w10: here is "wrong" move order. You first hane above :b1:.

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


Although this has been played - that's right - in a Korean game : D

The timing of the original :w1: below is suspect. However, the story is a little more complicated. Pushing up at :w1: at this point appears in over 300 games in GoGoD. So the problem is not obvious. :b2: first appears in GoGoD played by Japanese amateurs at the beginning of the '70's. Kim In then came up with :w3: as a reply. This variation was played a few times over the years in Korea but without clear success for Black. As a result, the connection at :b2: as a reply to :w1: has not appeared since 1990.

Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . X . . O O X . . |
$$ | . . . . . . . . . . . . . O X . 2 . . |
$$ | . . . . . . . . . . . . . 1 X . X . . |
$$ | . . . . . . . . . . . . . 4 3 O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |[/go]


The more thematic issue is the reply of :b2: to :w1: below (the "normal" choice of :w1:). Note that White can not continue with a play at 4 because :b2: has taken away a liberty, making the cut at 'e' more threatening. So White goes back and connects at :w3:. Play normally proceeds up to :w5:. Black has gained in the upper right corner while :w3: fixes White's cutting point and does a better job of undercutting the top. So why doesn't Black do this all the time? One point is that in the future White looks for the opportunity to descend at 'a' which Black can't resist too strongly because of the weakness in the shape here. So this variation is rare in the main line. However, if White first exchanges 'b' for 'c' before playing :w1:, it is much easier for Black to descend at :b2: because the marked White stone has been significantly weakened by the addition of a Black stone at 'c'. All that said, however, in most modern games in GoGoD Black just goes ahead and connects at 'd' anyway without attempting anything tricky. Black seems satisfied with reverting to the normal order of events. :blackeye:

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

Author:  SoDesuNe [ Fri Feb 08, 2013 4:43 am ]
Post subject:  Re: 3-4 joseki question

Thanks for the clarification! I got my information from the Sensei's page.

(Luckily I get my Joseki book back today ^^)

Author:  Uberdude [ Fri Feb 08, 2013 5:46 am ]
Post subject:  Re: 3-4 joseki question

Here's a game of a friend of mine where he got tricked by a move which ends up also leading to the 2 hanes gain an extra liberty shape (but there was a long ko left and he still won :) ).


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