Charles Matthews By the way, Black left an incomplete formation:
here is compulsory - see bulge.
Charles So I think is probably correct next, and then is at least very logical. One can then ask about White's subsequent invasion at a. I would say that is too deep, now. Black could try to kill it. A white shoulderhit at b, for example, is a more reasonable way.
Bill: It's hard to say too much without seeing the rest of the board, but may be a good idea. Also, looks clearly misplaced.
Charles Here Black might next look at playing a. Since the value of plays in the centre is to do with the large-scale picture, it is as Bill says: not enough context to be close to conclusive.
JoelR: I presume this is the sequence leading to the BQM. If ends up misplaced, then what should change? It looks to be a valid answer to . Is on the wrong side? Having a horizontal wall separating from doesn't seem to work well with Black's upper right. I note that SL doesn't have a page 4-4 point low approach high extension, 3-3 invasion?.
Bob McGuigan: I think above is a mistake. White gets too much territory in the corner. If Black wants to defend the top side I would expect something like this (as shown on the main page):
White's territory in the corner is less than in the game position. But whether it makes sense to block this way depends on the whole board position and that on the left side particularly.
Alex: Yeah, the point is that, even if Black wants to block off the top eventually (with here instead of at a), making the / exchange first gives White less territory and makes Black's stones slightly more coordinated, although is still too close. So, why does White play and allow Black to block off the top side after all? Because gives Black enough support that he can hane at instead of playing b, so White will have shape problems.
Charles Certainly this is correct. I was interested to see in pro games that is not played ( at is the common play here). Invading at 3-3 makes Black very solid on the left, in this line. That in turn makes Black's enclosure look even better.