Life In 19x19

Posted: **Sun Sep 11, 2011 2:53 pm**

The diagram below :b2:

is a commonly-identified (local) mistake. Of course, as with many such moves, there must be special cases for it. The position below is from a game between Yi Se-tol (Lee Sedol) and Ch'oe Ch'eol-han (both 9p). The position looks pretty normal, so I'm having trouble finding the reason for :b2:

. I assume it has something to do with attacking H3, which would (and did) lead to a running fight (after white responded at C3, black pincered at K3). Moreover, in my database (GoGoD, SmartGo, and some individual games I've added), :b2:

is the second most commonly played move in this joseki, albeit a distant second (nearly 600 for J4, and 109 for D2). Anyone have any insight into when this it is better than J4? Is it just when black wants to develop long the bottom or lower-right?

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

Posted: **Sun Sep 11, 2011 4:47 pm**

Pro opinion has changed. See the first sgf in Bill's post: viewtopic.php?f=10&t=4621&p=77638&hilit=sanrensei#p77638. (Good timing to ask that so soon after that thread).

Posted: **Sun Sep 11, 2011 5:53 pm**

But even if pros are reevaluating the pros and cons of this move, the cons are still there... Bantari posted a (imo) great discussion of the weaknesses of this shape a while back.

http://www.bantari.com/go/writings/blooper_001.php

Posted: **Sun Sep 11, 2011 10:26 pm**

If black was Lee Sedol, then his choosing it was reason enough. I'm pretty sure he doesn't play by proverbs. ;-)

Seriously, though, my feeling is that this move is played if you want to prevent this:

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . O . . X . . X . . . . O . O O O . | $$ | . . . O . . . . . , . . . . X X X O . | $$ | . . . . . . . . . . . . . . . . X X . | $$ | . . O . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . X , . . . . . , . . . | $$ | . . . . W X . O . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

I guess you probably already figured that, but it's explanation enough for me. :-)

Posted: **Mon Sep 12, 2011 2:07 am**

Black 2 makes it about impossible for White to defend a group developing from H3 by cutting at F4.

Otherwise it is all about whether one expects Black C3 to be reasonable later.

Posted: **Mon Sep 12, 2011 2:25 am**

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

This is a relatively little-used joseki that dates back to the 50's at least. Black generally wants to pincer from a Black position in the lower right, as in the case cited. Most often the pincer used has been :b4:

but "a" and "b" have also been played (according to GoGoD). Go Seigen's comment (in Bill's post referenced above) that an immediate "c" is important has not been embraced by the rest of the pro's, although it has been played a few times. The game cited continued as below. It is Game 1 from the 25th KBS Cup Final, played 2006-10-23.

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

Posted: **Mon Sep 12, 2011 9:54 am**

ez4u wrote:
$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . X . . X . . . . O . O O O . |
$$ | . . . O . . . . . , . . . . X X X O . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . O . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . d . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . c . . . . . . . . . . . . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . O . . . . . , a . . . . , . . . |
$$ | . . 3 . . X . O . 4 b . . . . X . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+

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

This is a relatively little-used joseki that dates back to the 50's at least. Black generally wants to pincer from a Black position in the lower right, as in the case cited. Most often the pincer used has been but "a" and "b" have also been played (according to GoGoD). Go Seigen's comment (in Bill's post referenced above) that an immediate "c" is important has not been embraced by the rest of the pro's, although it has been played a few times. The game cited continued as below. It is Game 1 from the 25th KBS Cup Final, played 2006-10-23.
$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O . . X . . X . . . . O . O O O . |
$$ | . . . O . . . . . , . . . . X X X O . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . O . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . d . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . . . . 3 . 4 . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . X . 2 . . 7 . . . . 8 . . . |
$$ | . . . O . . . . . , . . 6 . . , . . . |
$$ | . . O . . X . O . 1 . . . . . X . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

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

About Go Seigen's comment:

I think that the existence of a White stone on the left side star point ("d") is what makes the second jump better than the pincer. It is that stone that makes :w4:

in the second diagram a strong attack. Without it, :b5:

is good.

Posted: **Mon Sep 12, 2011 10:28 am**

hyperpape wrote:Pro opinion has changed. See the first sgf in Bill's post: viewtopic.php?f=10&t=4621&p=77638&hilit=sanrensei#p77638. (Good timing to ask that so soon after that thread).

Very interesting - I had missed that.

Thanks for the comments. It amazes me how a widely rejected move can become accepted (and perhaps rejected again later). This one seems particularly interesting, since this is a "typical mistake" 10 kyus are taught to avoid.

Posted: **Tue Sep 13, 2011 6:07 am**

judicata wrote:
hyperpape wrote:Pro opinion has changed. See the first sgf in Bill's post: viewtopic.php?f=10&t=4621&p=77638&hilit=sanrensei#p77638. (Good timing to ask that so soon after that thread).

Very interesting - I had missed that.

Thanks for the comments. It amazes me how a widely rejected move can become accepted (and perhaps rejected again later). This one seems particularly interesting, since this is a "typical mistake" 10 kyus are taught to avoid.

I think this is one of those cases (much like the kick in response to a low approach), which you first want to make the move, you want to do so for the wrong reasons. Later you find out sometimes there are reasons it might be good...

Life In 19x19

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