I was going through Lessons in the Fundamentals of Go again, when this position came up.

Black to answer .

Click Here To Show Diagram Code

[go]$$c
$$ ---------------------
$$ . . . . . . . . . . |
$$ . . . . . . X O . . |
$$ . . . O O . X O . . |
$$ , . . O X X , . O . |
$$ . . . O . . . O . O |
$$ . O O X X . X X O . |
$$ . . X . . . X . X . |
$$ . . . . . . . X . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |
$$ . . . . . . . W . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , O . . |
$$ . . . . O . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ ---------------------[/go]

Here's the solution by Toshiro Kageyama - and my question.

The book's solution follows the advice to push your opponent toward your strength when attacking. After B3 shown here

Click Here To Show Diagram Code

[go]$$c
$$ ---------------------
$$ . . . . . . . . . . |
$$ . . . . . . X O . . |
$$ . . . O O . X O . . |
$$ , . . O X X , . O . |
$$ . . . O . . . O . O |
$$ . O O X X . X X O . |
$$ . . X . . . X . X . |
$$ . . . . . . . X . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |
$$ . . . 2 . O . O . . |
$$ . . . . . a . . . . |
$$ . . . . . . . . . . |
$$ . . . 3 . 1 . X . . |
$$ . . . . . . . . . . |
$$ , . . . . . , O . . |
$$ . . . . O . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ ---------------------[/go]

White's running group still is under attack and White's corner is vulnerable to invasion. If White defends the corner then Black gets ahead in the running fight. Remember, "punishing" a mistake does not mean that your opponent's position collapses, just that you get an exploitable advantage.

I remember having read the same example and having asked myself exactly the same question. I probably could not answer then but when I think now, I come up with the following answer (without being sure):

Indeed it looks like black is the one under attack. However, white does not get anything useful from his attack because the black group at the upper side is strong. He neither gets decent profit, nor useful power for attacking any specific group. Even if white manages to capture the black stones (at r6,p6,etc) black can still get a compensation in the corner. But that's the interpretation of an eternal kyu player

_________________
If you say no, Elwood and I will come here for breakfast, lunch, and dinner every day of the week.

The point is that the black group above is completely alive and strong. There is no sense in trying to help or attack this group. When you have such a group in the vicinity, you have free hand to attack and invade your opponent's frameworks. That is why the white move was a mistake: it does not make territory, and it does not protect the white corner; it just presents a target. When Black invades as shown, the white stone and the black stone are almost equally weak, but while the black group above is very strong and not attackable, the white corner below is becoming very thin as the black stone strengthens itself against the weak white stone.

White should have played much closer to his corner, e.g. a simple two-point jump.

Click Here To Show Diagram Code

[go]$$c
$$ ---------------------
$$ . . . . . . . . . . |
$$ . . . . . . X O . . |
$$ . . . O O . X O . . |
$$ , . . O X X , . O . |
$$ . . . O . . . O . O |
$$ . O O X X . X X O . |
$$ . . X . . . X . X . |
$$ . . . . . . . X . . |
$$ . . . . . . . . . . |
$$ , . . . . . , . . . |
$$ . . . . . . . C . . |
$$ . . . . . . . . . . |
$$ . . . . . . . W . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ , . . . . . , O . . |
$$ . . . . O . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ ---------------------[/go]

_________________
A good system naturally covers all corner cases without further effort.

Thanks for all replies, it looks like I still have to tweak my feeling of a good and bad sequence.
In the end, white gets no territory out of his three stones, and only destroys maybe 10 black points. (if black did not attack but play defensively) Blacks three stones increase the aji in the corner, don't let white make any territory around black 1, and maybe even helps on the lower side.
I guess there is no way around actually playing moves like black 1 myself to get used to it, understand the move and see the actual profit in my own games.


I will try to not forget this anymore.