BQM 463

    Keywords: Question
How to exploit?  

tapir: in a recent blitz game my opponent tried to play similar to a known sequence when the marked black stone is a near approach. how can i exploit this best. connecting at a in sente, or starting big fight with b? in the game i played the second one and got a nice result.

How to exploit?  

Herman: b doesn't really work. White should have split black immediately

tapir: Hmm. So white made the bigger mistake... :( Thank you for the comprehensive answer.

Herman: I don't think it is the bigger mistake, actually. If black had played B3 immediately, instead of the overplay B1, then white can reasonably ignore and play tenuki. Exchanging B1 for W4 then becomes a good followup-for black. Later, white can play endgame with W6-B5-W2-B7, and you get the situation in this diagram. So I think the result is not bad for either player, but is par for the situation if white takes sente (As opposed to the "correct play" diagram below, which is gote for white).


Herman: This W6 really hurts the black+circle stone. But black needs a move in the corner, so has no time to respond.

Herman: a further note: B3 is the real error in this diagram, black should play a, as shown below by Bill.


Andy: To avoid the punishment, black might try to play as in 4473enclosure33invasion, which seems less bad, since black will end in sente and be able to do something about black+circle. Still, one has to think B1 is misplayed here.

Herman: instead of W4, white should stretch (to B7). See also the sequence posted by Bill further down.

Punishment? pt 2  

B5? hard to find a great move for black here.

tapir: If white tenukis now, can she still resist Black a later? (If the ladder isn't working for white.) I think she can't, so B5 is kind of sente, isn't it?

Herman: Yes, the black move at a is good aji for black.


As a follow-up, white can play something like this.

Note though, that black had perhaps better choose to forgo B2 and instead jump out to a in response to W1. It is a success for white anyway, as black will have a weak group in white's sphere of influence...

Correct play  

Correct play for black would have been this B1. Black should play this early, because a white move at a would take a big corner while attacking black.

tapir: basically i didn't play a earlier because I wasn't sure that it takes the corner and don't want to play moves while knowing that i don't understand them.

Herman: After a, white may still lose the corner, but only under unusual circumstances, in which case white is probably getting plenty of compensation elsewhere. In this position, a is the only move played by professionals if they get first move in this corner. (For black, B1 is the most common, but invading at 3-3 is possible, as bill shows below.

Bill: Without the extension, the 3-3 invasion is not good. However, with the extension I had questions. A GoBase search showed several examples, even at the highest levels.

Simple variation  

Bill: White is overconcentrated, but Black is low, and also a bit overconcentrated. And White gets sente.

Frequent variation  

Bill: When White blocks with W2, Black typically lives with B3 and B5, without playing the hane. The stretch, W4, is solid. After B5 White can tenuki.

BQM 463 last edited by BobWhoosta on February 20, 2011 - 03:13
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