A question about star one-space low clamp 33 invasion

This is a question about start point one-space low clamp 33 invasion.

Attached #1: Diagrams A-1-3-1-2-1 and A-1-3-1-2-2 from AI Go Joseki Dictionary, which says both diagrams are good for white.

Attached #2: My question is after A-1-3-1-2-1, if white tenukis, and black plays like this (15-21) diagram, white is fully sealed off in the corner, is this really good for white?

20211012 A-1-3-1-2-1&2-02

Your comments are much appreciated.

For evaluating joseki results, you always need to take into account the number of moves playes by each side. In your latter diagram, white played 9 moves and black played 11 moves.

So yes, locally black seals white in while making a nice wall on the outside, but in return white gets a safe and fairly large corner and 2 extra opening moves elsewhere (like corner approaches or corner enclosures).
Taking that into account, I think black’s gote continuation would be somewhat slow to play immediately (in the early opening). So in practice, the continuation after A-1-3-1-2-1 would usually be that both players play elsewhere for a number of moves, before returning to this corner.


It’s something i see sometimes in classical pro games at different stages of the game where a player takes two time gote but then a huge sente. Makes thinking even deeper on this sente/gote.

Note also that if black did this too early, white need not answer 19 at 20 but can tenuki AGAIN to a big opening point, though black then capturing at h1 in sente is pretty nice (but perhaps not as nice as that extra tenuki white got).


I don’t know how AI feel about this, but I feel that black blocked on the wrong side with 1.
AFAIK, black only does that when he already has the left side star point (and maybe one more in the upper left corner), because black loses sente blocking from the direction of 1, so he may not be able to extend from that wall. At least that would be the classical thinking.


Yes, it’s what this books says as well. The first sentence of A-1-3-1-2-1 reads:
Even if black has support on the left side, black 1 to block from outside is not very good.


Yes it’s good for white. But be aware that the advantage isn’t very big. I guess the loss for black is about 1 point, by no means >2 points, if the rest of the board is almost empty.