After my favorite pincer, there's a currently popular joseki line that I don't understand. starts the joseki, at which point and are inevitable. In the pictured position, White a followed by Black b are the most common continuation. But white has tried c, d, e and f.

Click Here To Show Diagram Code

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

My question is really vague: what's going on here? Why/when does Black make this choice, and what is he hoping to accomplish?

_________________
Occupy Babel!

Well, another common variation with this joseki is, instead of Black playing 'b', he makes a two-space extension off the marked stone and then White plays 'b'. This clearly emphasizes the value of 'b'. Why is it valuable? Well, I don't think it's any more complicated than the fact that it either gives or loses White the corner, depending on who plays there first. 'a' is necessary before 'b' because it is the lesser of the two defects with this corner. If White gets both 'a' and 'b', then not only is White guaranteed alive, but more importantly Black is separated into two groups that aren't necessarily stabilized. However, if Black gets 'b' then the top group is definitely safe. Hopefully I've emphasized the value of 'b' well enough.

Now regarding the follow-up after Black plays 'b', White's corner is now pretty beat up and it would be too submissive/slow to respond to 'b' directly by descending to the second line. At the same time, White's group isn't strong enough to aggressively pursue the marked stone, so the best she can do is to move out and gain strength and access to the center, either forcing Black to reinforce the marked stone by extending from it or play a big point elsewhere to allow White the opportunity to attack the marked stone (if it's important on the whole board).

That's just my thoughts...didn't refer to a dictionary or anything like that to verify whether my thought process is indeed correct.

Actually, based on DailyJoseki.com, white plays a close pincer after black plays :

Click Here To Show Diagram Code

[go]$$B
$$ ------------------
$$ | . . . . . . . . .
$$ | . . 1 X . . . . .
$$ | . . O X . . X . .
$$ | . . . O . . . . .
$$ | . O . O . z . . .
$$ | . . . . . . . . .
$$ | . y X c b . . . .
$$ | . . . x . . . . .
$$ | . . 2 . . . . . .
$$ | . . . , . . . . .
$$ | . . a . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

If black controls the bottom left corner, he might counter-pincer around 'a'. White 'x' is then played in all three games in the DB that reach this position. Or, black might respond with b or c, following which white plays y or z, respectively.

_________________
We don't know who we are; we don't know where we are.
Each of us woke up one moment and here we were in the darkness.
We're nameless things with no memory; no knowledge of what went before,
No understanding of what is now, no knowledge of what will be.

I should clarify what I was asking about: I want to know the idea behind the entire joseki. a and b seem pretty clear on their own, though the continuations for white are a bit less clear. But why play in the first place?

_________________
Occupy Babel!

This was one of my favourite tricks for a little while. Someone pointed out in my study journal the following link on this joseki:

http://www.badukaires.com/2010/07/24/el%20...%20nightmare/

The link is in spanish, but Google Translate doesn't do too bad a job of translating, I guess.

Anyways, I'd have to get back to studying it before I could tell you in any detail what the ideas are behind this. It gives up the corner, more often than not, and I've never truly been able to use it successfully unless my opponent makes a mistake in the sequence.

Anyways, I've stopped throwing this joseki down on the board in every game I played. I'm currently of the opinion that this joseki requires a very specific plan ... and I'm not sure exactly what kind of plan is needed.

Marcus, you seem to have copy-pasted the '...'s in the url. Here's the actual working url:
http://www.badukaires.com/2010/07/24/el-joseki-spanish-nightmare/

_________________
We don't know who we are; we don't know where we are.
Each of us woke up one moment and here we were in the darkness.
We're nameless things with no memory; no knowledge of what went before,
No understanding of what is now, no knowledge of what will be.

Wow, how did I miss that?

I think it's played when white has influence on the right side - you give some up in the corner to play fast across the top side and keep it from expanding into a moyo. At least, that's the sort of situation in which I consider it - which may be totally different from what a stronger player thinks.