Life In 19x19

John Fairbairn wrote:

How bad is the attach and block joseki?

It has always made me feel uneasy, because it accepts a "bad" shape.

There is an interesting example in this case. He starts off by saying that the reason tsukeosae disappeared was, in a nutshell, because of the empty triangle. However, he also gives another way of looking at it (which is more attuned to AI insights, perhaps). And that is that the tsukeosae side should feel uncomfortable about giving the opponent the atari that creates the empty triangle.

Uberdude wrote: one of the lessons I've picked up from bots is how much they dislike letting the opponent make gains in local efficiency of shapes in sente*, even if there is a directional benefit to it.

Example 14.

Guo Yuzheng, 3 dan (W) vs. Chang Hao, 9 dan

GoGoD 2013-05-09i

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[go]$$Bcm17 Jump attachment playable, block minor mistake
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 6 . . . . . |
$$ | . . O . . O . . . . . . . O 3 . . . . |
$$ | . X . O . . . . . , . . 2 1 5 X . . . |
$$ | . . . . . . . . . . . . . 4 . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . , . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Again, not too surprising, as Black only has something on the right side, while White has something on the top. As usual, Elf recommends the kick and the nobi.

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[go]$$Bcm17 Mainline variation for the kick
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 9 . . . . |
$$ | . . O . . O . . . . . . . O 1 . 8 . . |
$$ | . X . O . . . . . , 4 . . 2 . X . . . |
$$ | . . . . . . . . . . . . . . . . . 6 . |
$$ | . . X . 5 . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . 7 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . , . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

In the old days the kick would have been questionable, as it strengthens White without any obvious attack. makes only a 2 space high extension. plays on the frontier of two frameworks. Then plays a submarine invasion, aiming both ways. blocks off the side, and occupies the 3-3. The descent, , aims both ways.

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[go]$$Wcm26 Mainline variation for the kick, continued
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . 7 . . . . . . X . . . . |
$$ | . . O . . O . 9 8 . . . . O X . O . . |
$$ | . X . O . . 6 . . , O . . O . X 1 . . |
$$ | . . . . . . . . . 0 . . . . . 2 . O . |
$$ | . . X . X . . . . . . . . . . X . 5 . |
$$ | . . . . . . . . . . . . . . . . X 3 . |
$$ | . . . . . . . . . . . . . . . . . 4 . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . , . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

- secures the corner group with gote. Then leans on White group in the top left with a shoulder blow. slides to the second line, but makes another shoulder blow on the 3d line, keeping the White groups separated. After White pushes up with , attacks the White group in the top right side with another shoulder blow. Note that , , and form a dogleg keima shape.

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[go]$$Bcm19 Mainline variation for the nobi
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 6 . 2 . 4 . . |
$$ | . . O . . O . . . . . . . O 5 . 3 . . |
$$ | . X . O . . . . . , . 8 O X . X . . . |
$$ | . . . . . . . . . . . . 7 1 . . . . . |
$$ | . . X . . . . . . . 9 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . 0 . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . , . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

After the nobi, and are usual. Then plays to stabilize the White group with strengethening Black too much. Still, Black gets the turn, , with sente and then plays the double keima with . Then plays a shallow reduction on the right side.

Follow-up to the attach and block

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[go]$$Bcm23 Mainline variation for :b23:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . 6 . O 8 . . . . |
$$ | . . O . . O . . . . . . . O X . . . . |
$$ | . X . O . . . . . , 5 2 O X X X . . . |
$$ | . . . . . . . . . 0 4 3 1 W . . . . . |
$$ | . . X . . . . . . . . . . 9 . . . . . |
$$ | . . . . . . . . . . . 7 . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . , . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

cuts in sente, as extends. In the skirmish pushes, blocks, and cuts. makes eyeshape. Then jumps into the center. turns on the 2d line, threatening the corner. grabs the stone, securing the Black stones. Then fortifies White's top side.