This is a position from one of my games. Up to now, if I wanted to kakari the top left (I'm White), I played A without thinking much, because I have a good porspect of territory from the left stones.

But I realized that :
- I'm using thickness to make territory
- I'm helping Black to overpower he left edge

So I wonder if it's really a no think move... and played B

What do you think ?

Click Here To Show Diagram Code

[go]$$Bm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . a . . . . . . . . O O X O .|
$$ | . . . X . . . . . , . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . b . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

Don't underestimate this move ...

Click Here To Show Diagram Code

[go]$$Bm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . a . . . . . . . B O O X O .|
$$ | . . . X . . . . . , . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . b . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

I would not consider the White position in the upper right thick. I'm interested to hear what players stronger than me think.

I'd play at your a, expecting one of the following:

Click Here To Show Diagram Code

[go]$$Wm1
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . 1 . . . . . . . . O O X O .|
$$ | . . . X . . . . . 3 . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . 2 . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

Click Here To Show Diagram Code

[go]$$Wm1
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . 5 . . 1 . 2 . 3 . . . . O O X O .|
$$ | . . . X . . . . . . . . . O X X O O .|
$$ | . . . . . . . 4 . . . . . O X O X X .|
$$ | . . . . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

Come to think of it, maybe I'd play here first:

Click Here To Show Diagram Code

[go]$$Wm1
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . O O X O .|
$$ | . . . X . . . . . . . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . . . . . . . . . . . . 1 X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

It looks pretty forcing.

You're right Let's assume your marked stone is white then

I think that your reasoning is good (though depending on the thickness, I don't think a is actually wrong, and is probably often quite right), but that your thickness isn't:

Click Here To Show Diagram Code

[go]$$Bm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . 1 2 .|
$$ | . . . . . a . . . . . . . 3 O O X O .|
$$ | . . . X . . . . . , . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . b . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

This doesn't quite devastate white's position, but it's very annoying, and black won't need to try very hard to make it work fully.

I'm going to steel the diagram from dfan. to give my view on this.

Click Here To Show Diagram Code

[go]$$Wm1
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . 1 . . . . . . . . O O X O .|
$$ | . . . X . . . . . 3 . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . 2 . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

the proverb "building territory with you thickness is bad"
This would apply if you played 3 first, building territory with you "wall" therefore playing 3 first is bad according to the proverb and I agree with that. It allows black to play at 1. this takes away any further development of the top for white, while black has just gotten a nice move in the corner to turn the left in a lot of potential for black.

The top left corner approach at 1 looks like a good move. It is far from the wall, so rather than building points with the wall you are using it to create potential (a good thing).
If your opponent plays 2 you can play 3 (like in the diagram). now 3 is a good move, because first and foremost 3 is there as a follow-up on the 1 stone, secondly as an EXTRA it is creating territory with the wall.
this makes the move at 3 a dual purpose move and therefore a strong move.

if your opponent resists like dfan also showed then black gets a weak group and you can expect some attack later.

side-note
The top right is indeed weak and the cutting-points really are a problem, (but that was not part of your question).

_________________
Laurens
Go school: freegame's Teaching School
Author of: The Next Move a book for 15-3kyu players.

for your argument purpose i will change one thing on the board..
what you see at the bottom is not a example of building territory using thickness.
it is a perfectly good move.

Click Here To Show Diagram Code

[go]$$Wm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . W . .|
$$ | . . . . . 1 . . . . . . . . O O . O .|
$$ | . . . X . . . . . 3 . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . 2 . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

somethig like this is a good example of building territory using thickness.

Click Here To Show Diagram Code

[go]$$Bm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . W . .|
$$ | . . . . . a . . . . . . . . O O . O .|
$$ | . . . X . . . . . , . . . O X X O O .|
$$ | . . . . . . . . . . . . . O X O X X .|
$$ | . . b . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . 1 . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . X . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

_________________
"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson

Thanks for answers. And for noticing defect in my shape But don't add anything on the subject, the game isn't over yet. If I lose it, I'll post for review, because it's fun for the time being.

Extending is not building territory. If you assume that the white shape in the upper right is actually settled (which it is not), 'a' is the right move: it is the most open area on the board, and both sides are high and active there. On the left side, Black is low.

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

I like a better. Seems to have better potential, while b seems to remove potential.

_________________
a1h1 [1d]: You just need to curse the gods and defend.
Good Go = Shape.
Associação Portuguesa de Go

Click Here To Show Diagram Code

[go]$$Bm27
$$ +--------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . a . . . . . . . C O O X O .|
$$ | . . . X . . . . . , . . . W X X O O .|
$$ | . . . . . . . . . . . . . W X O X X .|
$$ | . . b . . . . . . . . . . . X . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . X . . .|
$$ | . . . , . . . . . , . . . . . , . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . B . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . X . X . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . X . O . . . , . . . O . O . . .|
$$ | . . . . X O . . . O . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ | . . . . . . . . . . . . . . . . . . .|
$$ +--------------------------------------+[/go]

Let me ignore the defect and assume that there is a white stone at

To choose between a and b, you have to ask whether which side is more interesting. The top side has quite a lot of development potential because white has a wall at . The left side has less potential for development, especially because is low. Therefore, the top side is more interesting than the left, and white should choose a.

_________________
My homepages: http://senseis.xmp.net/?Unkx80 and http://yeefan.sg/.

And if your marked black stone was on the fourth line ?

Then a black pincer (after white at b) would be a thing of beauty...

_________________
That which can be destroyed by the truth should be.
--
My (sadly neglected, but not forgotten) project: http://dailyjoseki.com

My conclusion remains the same. Just look at how many moves white has invested on the top side versus how many moves black has invested on the left side.

_________________
My homepages: http://senseis.xmp.net/?Unkx80 and http://yeefan.sg/.