John Fairbairn wrote:
The fact that B is a tad unsatisfactory for White, suggests to me (as does Black's overconcentration) that there have been errors by both sides in the play so far, so subsequent moves are likely to be blighted by that. But going with what we have, since B for White is imperfect and capturing the corner for Black has the effect of removing much of his own overconcentration, I think a strong case can be made for A, preventing Black from taking the corner A and White thus facing the risk of Black making use of the aji on the left side. If that happened, White would end up with overconcentration, cancelling out Black's - but Black would have more points in the bag already.
This appears to be a 2 stone game, and Black does appear to be overconcentrated. Without going into Black's aji if he takes the corner, let's see how that might affect Black's overconcentration.
First, let's look at the situation if White takes the corner.
- Click Here To Show Diagram Code
[go]$$Wc White takes the corner
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O O O 4 . . . . . . . . . . . . |
$$ | . . X O X X . . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | O . O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | 3 X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | . O O O X . . . . . . . . . . . . . . |
$$ | . 1 X X 2 . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
I expect that White will reply to
, but let's leave that discussion for later and do some tewari in the corner.
- Click Here To Show Diagram Code
[go]$$Wc Tewari
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O O O X . . . . . . . . . . . . |
$$ | . . X O X X . . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | w b O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | w b O X . . . . . , . . . . . O . . . |
$$ | . B O X X O . X . . . . . . . . . . . |
$$ | . O O O X . . . . . . . . . . . . . . |
$$ | . O X X X . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
The w's and b's represent Black and White stones that are paired. Black has made a wasted play in the corner, represented by the
stone. The Black C-08 stone is pretty much a goner, but the White F-03 stone is in bad health, as well.
Now let's look at the case where Black takes the corner.
- Click Here To Show Diagram Code
[go]$$Wc Black takes the corner
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O O O . . . . . . . . . . . . . |
$$ | . . X O X X 1 . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | O . O X . . . . . . . . . . . . . . . |
$$ | b O X X . . . . . . . . . . . . . . . |
$$ | 3 X O X . . . . . , . . . . . O . . . |
$$ | a X O X X O . X . . . . . . . . . . . |
$$ | 2 O O O X . . . . . . . . . . . . . . |
$$ | . 4 X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
Perhaps Black will reply to
before taking the corner, but we leave that discussion until later. Before scoring we assume that Black will play at "a" and White will play at "b". Let's do some tewari in this corner.
- Click Here To Show Diagram Code
[go]$$Wc Black takes the corner
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O O O . . . . . . . . . . . . . |
$$ | . . B O # # O . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | W b O X . . . . . . . . . . . . . . . |
$$ | O O X X . . . . . . . . . . . . . . . |
$$ | O X w # . . . . . , . . . . . O . . . |
$$ | X X w # X W . B . . . . . . . . . . . |
$$ | b w w w B . . . . . . . . . . . . . . |
$$ | . b b b . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
As before, the b's and w's represent paired Black and White stones. Note that we cannot pair the
stone on A-06 with the captured Black stone at B-06 because of the presence of the
stone on C-08. Black could roll up the White stones there, starting with an atari at A-06. That might change later, but we don't know. So we have paired that Black stone with one of the captured White stones. If anything, Black's corner is less efficient in this diagram, with one or two wasted stones, represented by the
stones on D-03 and D-04. In addition, because of the hane in the center, the
stones on E-08 and F-08 are poorly placed. Whatever we may say about the aji on both sides, taking the corner has not alleviated Black's overconcentration.
Edit: Widening our scope a little beyond the corner, if we pair
on F-03 with
on E-02, Black's pincer (I assume),
on H-03, is much too close to the Black strength in the corner. Taking the corner has made Black's overconcentration even worse.