Life In 19x19

In eidogo, it is said that the following sequence is bad for white -- W6 should be in B7 instead.

Click Here To Show Diagram Code

[go]$$B
$$ -------------------
$$ - . . . . . . . . .
$$ - . . . 4 . . . . .
$$ - . . 7 . . 2 . 5 .
$$ - . . . 1 . . . . .
$$ - . . . . . 6 . . .
$$ - . . 3 . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .[/go]

However, the following sequence looks very playable for white, as the black pincher stone is under attack. Could someone enlighten me any misunderstanding that I have? Thanks.

Click Here To Show Diagram Code

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

In your diagram black isn't really under attack. Consider one more move.

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[go]$$W
$$ -----------------------
$$ - . . . . . . . . . . .
$$ - . 2 1 W . . . . . . .
$$ - . . X . . W . X . 3 .
$$ - . . . X . . . . . . .
$$ - . . . . . W . 4 . 5 .
$$ - . . X . . . . . .
$$ - . . . . . . . 6 .
$$ - . . . . . . . . .
$$ - . . . . . . . . .[/go]

Now the white stones are threatened. White can jump out too but there's no way he can keep ahead of black on both sides.

To answer your question though, consider the position without the slide which appears in this joseki.

Click Here To Show Diagram Code

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

A move at b is more profitable for white than a move at a, so he wants to try and settle his stones in a way that avoids the need to play a and thus preserves the option of playing b. Although the move order is different this shows us that white's position is inefficient if he creates that shape.

When you play the slide as white in this joseki you are saying that you want the corner. To not play on the 3-3 is being inconsistent. If you want to jump out then you need to do it immediately.

The problem with playing the jump is that white has a weak group coming under attack when there is no need to be weak.

Click Here To Show Diagram Code

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

If you play like this, white now is alive in the corner. Black cannot really harass white. Additionally, has removed black's base in the corner while making one for himself. This principle is common in go - a move that makes a base for both sides is important. The most common follow-up is this:

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[go]$$B
$$ -------------------
$$ - . . . . . . . . .
$$ - . . . O 2 6 . . .
$$ - . . O . 1 O 5 X .
$$ - . . . X . 3 4 . .
$$ - . . . . . . 7 . .
$$ - . . X . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .[/go]

White has modest corner potential and a hugely important ladder breaker move. If white has the ladder black should not play the original pincer move. Bringing out and splitting black in two is devastating as black's corner stones have no base.

...sooo, if Black wants the corner he should play at in moyoaji's first diagram and let white extend along the top?

TheBigH wrote:...sooo, if Black wants the corner he should play at in moyoaji's first diagram and let white extend along the top?

Correct!

And from that reasoning is where we get this common joseki:

Click Here To Show Diagram Code

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

I like to come up with a "story" or something to help remember the reasons behind each move in a joseki so that I don't just blindly memorize them. This is my "story" of the common 4-4 approach, small knight response joseki.

says "I want to develop one side of the board or the other, top or left. Also, I'm not all that interested in the corner unless I get a big corner."

says "I would prefer you didn't develop the top. Instead, you can develop the left. Also, I notice that you don't care much about the corner. If you don't want it, can I have it?"

says "If you don't want me developing the top, that's fine, I'll develop toward the left. That corner is still up for discussion."

says "Okay, but you said earlier that you didn't care much about your corner. Can I settle in that corner?"

says "Actually, I would like to get some points in this corner and settle there myself. You can't settle here."

says "Okay then, I'll settle on the top of the board."

All in all, a very peaceful joseki.

An important consideration with this joseki (the one moyoaji posted) is also . At , black also said "I'll stay a bit lower and take less potential if you give me sente at the end."

As an alternative:

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------
$$ - . . . . . . . . . .
$$ - . . . 4 . . . . . .
$$ - . . 5 . . 2 . . 6 .
$$ - . . . 1 . . . . . .
$$ - . . . . . . . . . .
$$ - . . b 3 . . . . . .
$$ - . . . . . . . . . .
$$ - . . . . . . . . . .
$$ - . . . . . . . . . .
$$ - . . a , . . . . . .
$$ - . . . . . . . . . .[/go]

Here, black says with "I want to limit your top more, or build on a larger scale on the left than in that other joseki. In exchange, I will owe you a move somewhere around A, and so either I will give up sente soon to fix it, or you'll have the opportunity to take advantage of my weakness later."

It follows that if black already has a stone around A or so, there's usually not much reason to play at B. Black can play on a grander scale with this and still end in sente.

gostudent wrote:
However, the following sequence looks very playable for white, as the black pincher stone is under attack. Could someone enlighten me any misunderstanding that I have? Thanks.

$$W
$$ -----------------------
$$ - . . . . . . . . . . .
$$ - . 2 1 O . . . . . . .
$$ - . . X . . O . X . 3 .
$$ - . . . X . . . . . . .
$$ - . . . . . O . 4 . 5 .
$$ - . . X . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .

Click Here To Show Diagram Code

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

Black has one weak group, white two, so black is fine. But black has many other choices, one very easy one to avoid the pincer stone being attacked is:

Click Here To Show Diagram Code

[go]$$W
$$ -----------------------
$$ - . . . . . . . . . . . .
$$ - . . 1 O . . . . . . . .
$$ - . a X . . O . X . . 2 .
$$ - . . . X . . . . . , . .
$$ - . . . . . O . . . . . .
$$ - . . X . . . . . .
$$ - . . . . . . . . .
$$ - . . . . . . . . .
$$ - . . b . . . . . .[/go]

If white continues in the corner at a after blocking and white connect black extends to b to settle his group. Yes white is now alive, but it's smaller life than had he got the 3-3 point.

And more advanced:

Jump out in response to the pincer is locally bad for white and is not really considered joseki afaik. However, it can occasionally be good in the global situation, here is one example from Lee Sedol I saw recently.

Click Here To Show Diagram Code

[go]$$Wcm6
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 4 . . . . . . 6 2 . . 0 . . |
$$ | . . . O . . . . . , . . 5 . . X . 3 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 7 . . . . . . . . . . . 9 . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 8 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

The important thing here is he made the should hit at n16 and wants to make influence. I believe he also succeeds in making f17 for c14 a bad exchange.

Click Here To Show Diagram Code

[go]$$Wcm16
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . 2 . X X . . X . . |
$$ | . . . O . . . . . , . 1 O . . X . O . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . O . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 7 6 X . . |
$$ | . . . . . . . . . . . . . . . 3 4 . . |
$$ | . . . , . . . . . , . . . . . 5 8 . . |
$$ | . . . . . . . . . . . . . . . 9 . . . |
$$ | . . . . . . . . . . . . . . . . 0 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Full game here: http://www.go4go.net/go/games/sgfview/40678

Just for reference here's Lee playing the normal joseki a few months later: http://www.go4go.net/go/games/sgfview/41275