Click Here To Show Diagram Code

[go]$$W a - well known joseki, b- what's that?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 7 1 3 . 9 . . . . . . . . . . . . . |
$$ | . 5 2 X 4 . . . . , . . . . . , . . . |
$$ | . 6 . . . a . . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . b . . . . . |
$$ | . . . , . . . . . , . . . . 4 X 2 . . |
$$ | . . . . . . . . . . . . . . 5 3 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Why do people play the continuation in b? What are the pros and cons? What options are there to react?

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 7 1 3 8 . . . . . . . . . . . . . . |
$$ | . 5 2 X 4 . . . . , . . . . . , . . . |
$$ | . 6 . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

How would (a) be joseki? :)

How would I even start discussing with you? I'm no expert and don't know all the side variations of any joseki. I play that because I'm quite sure Guo Juan said so. That's all I can say as an argument.

To be more precise:

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . S . . . . . . . . . . . . . . . . . |
$$ | . S 1 3 c W . . . . . . . . . . . . . |
$$ | . S 2 X 4 . . . . , . . . . . , . . . |
$$ | . S . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

I remember that there is a variation of the invasion, where Black doesn't go to c but to 4 instead and ends up Sente, because white should play the marked white stone last. How the marked corner area develops I'm not quite sure. I'm absolutely sure that I never saw any theoretical material discussing c for the 5th move.

Normally, this is joseki:

Click Here To Show Diagram Code

[go]$$W
$$ +------------------
$$ | . . . . . . . . .
$$ | . . . . 3 5 . . .
$$ | . 9 O 1 2 4 6 . .
$$ | . 7 X X . . . . .
$$ | . 8 . . . . . . .
$$ | . . 0 . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

The stretch, instead of the hane, is only usual when the invasion comes after a pincer:

Click Here To Show Diagram Code

[go]$$W
$$ +------------------
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 9 3 5 b a . . .
$$ | . 7 4 X 6 . . . .
$$ | . 8 0 . . . . . .
$$ | . . 1 . . . . . .
$$ | . . . . . . . . .
$$ | . . 2 . . . . . .
$$ | . . . . . . . . .[/go]

Here, a is the usual next move for white, but sometimes white pushes at b instead. The purpose is to get sente.

This is probably what you are referring to?

You do not need to be an expert to understand that Black 8 in my variation is better (on the empty board). Since it is better, your more 5 is bad (on the empty board). But... the predominating opinion is that already 3-3 is bad early during almost all openings.



For the empty board?

***

Black's straight 4th line extension can be useful if Black wants sente, a thick wall and that wall showing to the right direction (for building a big moyo).

White's last move is a mistake, keima is normal. The reason is as below:

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . S a 8 7 b . . . . . . . . . . . . . |
$$ | . S 1 3 6 5 . . . . . . . . . . . . . |
$$ | . S 2 X 4 . . . . , . . . . . , . . . |
$$ | . S . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

If 9 at a, then black cuts at b and ladders the white stone or just extends if the ladder doesn't work - a better result for black. If 9 at b, then black plays a and takes corner while leaving white with an inferior position outside in comparison with this next joseki:

Click Here To Show Diagram Code

[go]$$W
$$ ---------------------------------------
$$ | . . . . . b . . . . . . . . . . . . . |
$$ | . S a 0 5 6 9 . . . . . . . . . . . . |
$$ | . S 1 3 4 7 . . . . . . . . . . . . . |
$$ | . S 2 X 8 . . . . , . . . . . , . . . |
$$ | . S . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

11 at a, 12 at b.

@Herman: Yes, probably you are right. Maybe I confused that variation in my memory.

@Robert: Of course your variation is better for black. Discussing would mean that I show you a move for white that makes it impossible for black to get such a good result and I can't do that.

@illluck: the red squares mean there are stones from black and white but it is not clear in my memory, who plays when and how. Sorry to state that not more clearly.

Regarding the pros of cons of the invader pushing vs 2nd line hane connect and then jump, as Robert said the hane connect is gote without a pincer stone so black can make the huge turn for 8 so it's a bunk sequence. With a pincer stone hane-connect and then jump is by far the most common, but I have occaisonally seen pushing in pro games. The cons of pushing are you make your opponent thicker and a big turn remains (if you tenuki), the pro is you can get sente.

This came up in a recent game of mine in which there was a pincer stone, but the hane-connect was gote (as h1 is white's sente for a lopsided ko). So I decided to push a few times to live in sente. Normally pushing is not so good as it makes your opponent thicker than the hane-connect and jump joseki, but in this game I don't made making white thick as that left centre area is his territory anyway; I'm never going to invade there. When I showed this game to a pro she said this was good.

Click Here To Show Diagram Code

[go]$$Bcm55 Push for sente (I was black)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . 9 X O . . . . . |
$$ | . . . 8 . . . . . . . O O X X . . . . |
$$ | . . 7 6 . . . . . O . X O X O . . . . |
$$ | . . 5 4 . . . X . . X O O X . . O O . |
$$ | . . 3 O . . . . O O O X X X O O X X . |
$$ | . . 1 2 . X . . O X X O O O X X . X . |
$$ | . . . . . . . . O X . X . . O X . X . |
$$ | . . . . . . . . . . X . . . . . X . . |
$$ ---------------------------------------[/go]

Seriously, there's no way to even really discuss this if you can't remember the actual shape - sequences and intentions change completely in the existence/absence of even one stone in the nearby area.

A couple of days ago this joseki appeared in a teaching game:

Click Here To Show Diagram Code

[go]$$W joseki
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . . 1 . . . . . . . . . . . . . . |
$$ | . X O O X . . . . , . . . . . , . . . |
$$ | . X X X O O O . . . . . . . . . . . . |
$$ | . . . X X O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

My pupil (White) played as follows:

Click Here To Show Diagram Code

[go]$$W application without thinking
$$ | . . X X X X . . . . . . . . . . . . . |
$$ | . . X O O O . . . . . . . . . . . . . |
$$ | . . X O X . . . . , . . . . . , . . . |
$$ | . X O . O . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . . 1 . . . . X . . . . . . . . . |
$$ | . X O O X . . . . X O . . . . O . . . |
$$ | . X X X O O O . . X . . X . O . . . . |
$$ | . . . X X O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I commented: "This move is a mistake, it should be played as follows:"

Click Here To Show Diagram Code

[go]$$W correct
$$ | . . X X X X . . . . . . . . . . . . . |
$$ | . . X O O O . . . . . . . . . . . . . |
$$ | . . X O X . . . . , . . . . . , . . . |
$$ | . X O . O . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . . a 1 . . . X . . . . . . . . . |
$$ | . X O O X . . . . X O . . . . O . . . |
$$ | . X X X O O O . . X . . X . O . . . . |
$$ | . . . X X O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Pupil: "But Guo Juan said that, in this joseki, I must always play at A to minimise aji!"

I: "Given your great thickness above, 1 is more efficient. It makes more territory. Due to the thickness, the usual aji does not become a problem. Guo should not teach proverbs but truths. The truth here is: USUALLY the joseki move is correct. Sometimes a different move can be correct."

I do not know whether my pupil reported correctly about Guo's teaching. The problem is the same as yours though: Do not blindly apply too general advice but always consider the positional context and adapt your moves accordingly!

Just because someone says Guo Juan said something, doesn't mean she did. Recently I was in a review on KGS where someone said something like "Guo Juan talked about this approach in a recent lecture". Her lecture had a 4-4 point, their game had a 3-4. Whilst there were some similar ideas, moving a stone one line does make quite a difference .

The pupil is a 1 dan, so he would not accidentally confuse one joseki with another. I asked him whether I have understood him correctly and he confirmed and insisted on Guo having indeed said what I have cited. Of course, I cannot verify it.

For sure, Guo knows that there are exceptions, but her pupils are not always aware that positional context plays an important role.

In Kageyama's Lessons in the Fundamentals of Go, he references a diagram saying that a strong amateur would say that this move is better. It makes more territory. It is superior to the simple move. He said all the pros he asked favored the simple "honte" move. Could this be such a case?

_________________
be immersed

Kageyama's example on pages 31 and 211 (3rd printing 1987) shows an otherwise empty part of the board. He writes on the joseki move: "The correct answer [...]" and "the firmer [capture] is correct". IOW, he overlooks another fundamental: that a non-empty positional environment (such as the nearby wall of another 7 thick stones in my game) can change the answer.

I once observed a 1k on KGS teaching a ~5k the large avalanche joseki, with a 4-4 as the initial stone in the corner.

The 1d pupil would not make such mistakes. He has knowledge gaps but is not stupid and would not make the kind of ridiculous mistakes you describe.

About the net vs firmer atari, your pupil is in good company at making that mistake (I agree it's a mistake), I remember recently reading a pro game commentary in which the pro made the same firm atari, when the net was better. But the small additional territory is not the only difference, indeed I think it is not the most important one here, and it certainly wasn't in the pro game. It is the fact that with the atari a becomes a sente peep for black which can be useful for the black group on the lower side. The pro game was, if memory serves correctly, remarkably similar though I think the black group was once one space to the left (oh the irony!) and was in fact under more pressure than your game, so that additional sente peep was a big help in settling that group.

Click Here To Show Diagram Code

[go]$$Wc Peep with firm atari
$$ | . . X X X X . . . . . . . . . . . . . |
$$ | . . X O O O . . . . . . . . . . . . . |
$$ | . . X O X . . . . , . . . . . , . . . |
$$ | . X O . O . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . . 1 . a . . X . . . . . . . . . |
$$ | . X O O X . . . . X O . . . . O . . . |
$$ | . X X X O O O . . X . . X . O . . . . |
$$ | . . . X X O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Maybe you should teach White how to avoid getting so overconcentrated instead of trying to optimize territory in a completely overconcentrated position. In fact, White could in this case probably play at something like ''a'' (in the diagram of Uberdude, jump out) outright not even capturing the Black stone directly at all.

Unless a lesson's teaching topics emphasise something else, there is not a "maybe you should" but there is an "of course I do". Since the topic here has emphasised something else (correct move when the position shown is already given), I have not mentioned it in this thread before.

In case of the joseki atari, Black always has such a peep available and would often use it when a group of his needs assistance. In case of the net, Black has other aji exploitation moves but in the game here the interesting ones are not so easily available. So currently the net captures more firmly than the atari, and this would even agree to Kageyama's idea.

Another aspect is territory efficiency (territory per invested stones).