In his ThePowerOfTheStarPoint, Shukaku Takagawa describes moves 1 and 3 "perfect timing," and "extremely big."
Is it just all about the aji? Taking gote here seems a pretty high price.
Bob McGuigan: I'd say these moves are sente in this situation.
Nick George: Bob, the next move is . Is that in response?
Bob: Well I'm no pro. But because the upper left lone black stone can be activated and the left side white area is open at the skirt on the lower left it doesn't look like White can make a lot of territory there. So I would want to answer on the lower side, because of the aji left there. But what do I know?
Thad: I'm sorry. I see how B a breaks the ladder, but I do not see how restores the ladder. Can you show a sequence?
HermanHiddema: does not restore the ladder, but before , a is a dual purpose move, breaking the ladder and threatening to play c. removes one of those purposes, so now if B plays a, W can answer at or around b
Nick George: ladder shmadder! A net would work fine.
HermanHiddema: What net? If B plays d, W descends and B cuts, there's a lot of aji. A ladder would certainly solve a lot of that. Breaking the ladder is not the main purpose of . It is a good move, expanding the W potential in the centre a lot. The ladder is just a detail.
Nick George: heh heh... nevermind... that kind of reading is what keeps me from reaching single digit kyu.
Bob McGuigan: Thinking about it a bit more I think is almost required. Imagine Black playing in that area. It is a junction of two moyos.
Jared: Perhaps a black play around a is more forceful now. White responding at b would be sente (threatening the corner) without the - sequence.
zinger: Wow! Can you show the sequence for that?
unkx80: and makes the invasion at much harder, because is sente. If Black ignores the sente move, kills. Subsequently, a possible variation is Black a to White d.
HermanHiddema: This sequence switches sente (so assumes that black plays tenuki first). I think zingers question was to show a sequence where black invades immediately at , white answers and B plays . After that, there is no realistic sequence to kill the corner really.