FWIW, and not to be disagreeable with anyone, but having stated fairly definitely that for White to allow Black the pincer and to pull back is a mistake in the past, I have found it not to be the case. Both from mid-high dan players and also from numerous professional games, this is a common way of preventing Black from kicking - something White may want if he has a position on the top and is trying to build big strength to attack.
$$B Variation 1
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . 6 . . . |
$$ . . 3 . 2 . . . . . |
$$ , a . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . . 5 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$B Variation 1
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . 6 . . . |
$$ . . 3 . 2 . . . . . |
$$ , a . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . . 5 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]
$$B Variation 2
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . 6 . . . |
$$ b . 3 . 2 . . . . . |
$$ , a . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . 5 . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$B Variation 2
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . 6 . . . |
$$ b . 3 . 2 . . . . . |
$$ , a . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . 5 . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]
In variation 1, dailyjoseki reports

as more common than "a" in professional games, albeit normally with a White stone on top (which is an important consideration before playing

it seems - odd, that used to be my favourite joseki in an open corner and open sides when I was around the 8-10k mark).
In variation 2, dailyjoseki reports

as considerably less common than "a" in professional games, although it's still the second most common and again normally has a White stone on top at "b". Interestingly, my recollection is that this is a common sequence when White starts out with an approach and then pulls back to "b" (or vice-versa, when White wedges in the middle of the orthodox and gets approached from the shimari, and responds here instead of the two space jump), expecting the invasion. Black often uses this to overconcentrate (see my latest Malkovich game against magicwand in the lower right):
$$B Variation 2
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . 8 . . . . . |
$$ W . 3 . 2 7 . . . . |
$$ , 6 . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . 5 . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$B Variation 2
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . 8 . . . . . |
$$ W . 3 . 2 7 . . . . |
$$ , 6 . . . . 1 . . . |
$$ . . . . 4 . . . . . |
$$ . . . . . . 5 . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |[/go]
So to say the slide is definitely aji-keshi seems to be rather overstating it. I suspect, as with all corner joseki choices, it's dependent on the rest of the board (or, in this case, the top edge at least). Certainly seems eminently playable with some purpose behind it
