Life In 19x19

The following is a joseki taken from http://eidogo.com/. However, I am not sure why this is equal result:

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . 4 6 7 . 3 .
$$ | . 8 1 5 2 0 . .
$$ | . . . . 9 . . .
$$ | . . . . . . . .[/go]

and then

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .[/go]

At the end, it seems that

* White lost two stones
* White is alive in the corner, but with a fair small territory
* With the two captured stones, black is fairly thick at the outside.

Thus black is advantageous in this outcome, and I'm not sure if this is joseki.

There are probably some flaws in my analysis. Can someone enlighten me? Thanks.

I feel like the result should go like this:

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . . . . 1 . . .
$$ | . a O O X . X .
$$ | . O X X O O . .
$$ | . b 4 3 X . . .
$$ | . . 2 . . . . .
$$ | . . c . . . . .[/go]

Now black can't capture white's two cutting stones anymore. In exchange, white has more weaknesses such as 'a' through 'c', but that seems like a worthwhile cost to me in order to save the two stones.

I can't say if the result is joseki or not, but it doesn't seem lopsided to me. Here are a few more things to consider:
* Black played first in the corner, so we can expect him to come out with a slight advantage.
* White is not enclosed - he has a stable position with access to the left side.
* There is some aji left in the two captured stones for white to get forcing moves on the outside.

gostudent wrote:

$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .[/go]

Thus black is advantageous in this outcome...

Takao agrees with you; he evaluates this result as "slightly better for Black".
He notes that if W is not satisfied with this result, W has other options.
Please see page 220 of his dictionary, volume 1.

White lived in sente and has one or two more sente moves to get in. A peep at a and some sort of liberty shortage tesuji at b. Also some what of a moral victory in that blacks strategy was probably built around enclosing the corner at the 3-4, so his stones on the outside and or bottom left might not be well placed, since if he wanted outside influence, black probably wouldn't play 3-4 in the first place, this is mostly speculation though.

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . a
$$ | . . . 3 X . 5 .
$$ | . . 2 b . . . .[/go]

Black's descent at 1 is a bit of a greedy move compared to solid connection at a, so if white sacrifices the 2 stones black has a somewhat nice result. The downside of the descent though is it means white can more readily save the two stones and fight with the sente push at 4 and then you'll get some big messy fight.

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . . . . 1 . . .
$$ | . . O O X a X 5
$$ | . O X X O O 4 .
$$ | . . 6 3 X . . .
$$ | . . 2 . . . . .[/go]

P.S. There are other choices for white 2 like extend or cut.

I've never liked joseki diagrams with an odd number of moves. It complicates the evaluation of the joseki because the you have to add a sente/gote differential in to your calculations.

I find it easier to evaluate if it is shown like this:

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . 6 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .[/go]

I admit that 6 is not joseki, nor is it needed, but it provides a visual statement of the relative benefits.

Originally it was considered a trick play and most famously used in this game between Takemiya Masaki and Cho Chikun. There's a full analysis of the sequence and game in Go World, Iss. 68. In short, as others have said, it's not considered an equal result.

Joaz Banbeck wrote:I've never liked joseki diagrams with an odd number of moves. It complicates the evaluation of the joseki because the you have to add a sente/gote differential in to your calculations.

I find it easier to evaluate if it is shown like this:

$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . 6 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . 6 . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .[/go]

I admit that 6 is not joseki, nor is it needed, but it provides a visual statement of the relative benefits.

Please don't do that.

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . O . . X . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . X X . X .
$$ | . . O . . . . .
$$ | . . . . . . . .[/go]

Black has played 8 stones, White 7 stones, the stone difference is 1.

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

Black has some 8 points, White has 7 points, the territory count is 1.

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . O . . X . . .
$$ | . . O O X . B .
$$ | . O X X O O . .
$$ | . . . X B . B .
$$ | . . W . . . . .
$$ | . . . . . . . .[/go]

Even if White plays the two forcing moves, they put only minor helping stones in front of the black wall. This changes only if White plays more stones to convert the helping stones into influence stones. So the possible helping stones are worth more than nothing, but only very little. Therefore, we can concentrate on the marked significant influence stones: Black has 3, White has 1, the influence stone difference is 2.

Stone difference = 1,
territory count = 1,
influence stone difference = 2,
slightly positive effect of white helping forcing stones.

The territory count is so small that it can almost be ignored, similarly the possible helping stones. This leaves these important factors:

Stone difference = 1,
influence stone difference = 2.

The stone difference 1 can be compensated by 1 imagined white influence stone elsewhere on the board (modifier -1 in White's favour for the influence stone difference). We get:

Compensated influence stone difference = 1.

Thus, (locally) the position favours Black! The thread title is wrong.

EdLee wrote:

gostudent wrote:

$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X B O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X B O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .[/go]

Thus black is advantageous in this outcome...

Takao agrees with you; he evaluates this result as "slightly better for Black".
He notes that if W is not satisfied with this result, W has other options.
Please see page 220 of his dictionary, volume 1.

Are you referring to this book?

http://senseis.xmp.net/?21stCenturyDict ... asicJoseki

Unfortunately, I cannot find this book in Amazon, and thus I do not have a convenient way to buy it...

Would you mind posting the sequence from the book on how to handle the circled black stone that can give equal results? Thanks!

EdLee wrote:

gostudent wrote:

$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ ----------------
$$ | . . . . . . . .
$$ | . 4 . . 1 . . .
$$ | . . O O X . X .
$$ | . O X X O O . .
$$ | . . . 3 X . 5 .
$$ | . . 2 . . . . .[/go]

Thus black is advantageous in this outcome...

Takao agrees with you; he evaluates this result as "slightly better for Black".
He notes that if W is not satisfied with this result, W has other options.
Please see page 220 of his dictionary, volume 1.

Black has played one more stone than White. So what does it mean to say that this result is slightly better for Black? OC, it is better for Black. But how does it compare to Black's original stone? That was certainly better for Black.

Certainly Takao means that this position is slightly better for Black than the original stone. But is he evaluating the original stone correctly? The tradition evaluation of a single stone in the corner is 10 pts., but we know that that is too low, because komi is more than 5 pts. Proper komi is around 7 pts, so a value of around 14 for the single stone is more accurate.

My guess is that this result is worth around 13 pts. I. e., it is slightly better for White.

gostudent wrote:Are you referring to this book?

Yes, Takao Shinji 9p's version, and the predecessor version by Ishida Yoshio 9p.

gostudent wrote:Unfortunately, I cannot find this book in Amazon, and thus I do not have a convenient way to buy it...

Please order the books from Kiseido, here:

http://www.kiseido.com/K41.htm

No extended excerpts, for copyright reasons.

RobertJasiek wrote:.....The stone difference 1 can be compensated by 1 imagined white influence stone elsewhere on the board (modifier -1 in White's favour for the influence stone difference). We get:

Compensated influence stone difference = 1.

Thus, (locally) the position favours Black! The thread title is wrong.

I appreciate your analysis but is it really that simple? You don't count for the resiliencys of both groups. Or stability, robustness or however you might call it. Maybe because they are about the same. I would swallow that but still it is a factor to be listed.
Also the cuttability of the white group at b15 seems a factor.

RobertJasiek wrote:
The stone difference 1 can be compensated by 1 imagined white influence stone elsewhere on the board (modifier -1 in White's favour for the influence stone difference). We get:

Compensated influence stone difference = 1.

Thus, (locally) the position favours Black! The thread title is wrong.

I'm skeptical of this analysis every time I see it. I don't think it takes nearly enough into account. Do other strong players accept this method of analyzing a position?