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BigQuestionMark

 

BQM32
  Difficulty: Advanced   Keywords: Question, Opening, Strategy

Here is a position from one of my games, with the last 10 moves marked out. I played Black.

[Diagram]
Diag.: Fuseki

My question is how to analyze the board, and what area's to be watching, where should I be on the guard for a reduction etc. As well as just in general, what the overall situation is with regard to who is ahead? My initial impression was that I was way ahead at this point, but I'm not really sure if I analyzed it correctly.

unkx80: I have no idea of the black move before white 1, but I think whatever the move, playing at a is too big.

BlueWyvern: If you are curious about the previous sequence, check it out here: PreBQM32



BillSpight:

You know, B 2 is a good play. But after allowing W 1, I hate to see White make a strong corner in the bottom left. I would like to put some pressure on White's stone there right away.
The double kakari at 3 comes to mind, but White can play at b, making Black a bit overconcentrated. And the 3-3 invasion looks like it will weaken the marked Black stone.
Somehow I want to play here:

[Diagram]
Diag.: Low kakari?

Now if White replies at a I'll be happy to play at b. ;-)

Is B 1 a reasonable play? Is it a hamete? Is it just another one of my brainstorms?

Little Question Mark: If Black plays against this corner, where should he play?



[Diagram]
Diag.: Evaluation

DaveSigaty: Blue, you asked how to evaluate this position. Let's see if we can survey the scene area by area:

  • Lower Half of the Board - White is completely dominant and has at least 30 points of solid territory already.
    • Lower Right Corner - as discussed on PreBQM32 allowing W to connect underneath has seriously weakened B while expanding W's territory. The marked B stones are essentially worthless now and the natural fate should be to end up captured by W (B should be interested in how to get W to spend time capturing them on a small scale).
    • Lower Left Corner - W has about 15 points of solid territory. I agree with Bill that B has unfortunately let W off easy here.
    • Lower Side - The fact that W is strong in both corners means that the two B stones on the lower side are thin and subject to attack. W should have in mind that if she can somehow limit B's prospects on the upper side in sente and play first here, she can reasonable expect to end up 50 points ahead of B on the lower half of the board by expanding her territory while attacking B. With this prospect before her, she can plan her strategies for the top.
  • Upper Half of the Board - Here the position is the reverse of the bottom (fair is fair :-), B owns the upper half. However, thus far B has nothing like the solid territory that W has claimed down below.
    • Upper Left Corner - The B 4-stone group in the upper left is very solid and has about 10 points of territory. The B 3-stone group to the left is also very solid but should be counted as only 4-5 points of territory. The W formation is very interesting for B and quite threatening for W because it has no base. B would very much like to attack this group. There is no real prospect of catching it. However, B has many opportunities to chase it. His problem is to decide what is the best way to do this. Should he attack from underneath, trying to drive it out toward the center and then hit it on the head to force it down the board while completing his framework on the right? Should he instead start from the center and attempt to force it into a cramped position in the corner?
    • Upper Right Corner - B has set up a classic Chinese style corner formation with extensions on both sides leading away from an open komoku. The main concern is that the formation is open on the right in the face of W's strong but low stone in the Lower Right. This stone is fairly distant, however, so B still retains good overall potential in the Upper Right. B is waiting now for W to use her sente to approach the corner. Realistically he needs a big result here as he is currently behind in territory and the score is likely to get worse not better on the lower side. On the other hand there is the weak W group floating in the Upper Left - W isn't home free yet.


[Diagram]
Diag.: Continuation....

These are the next five moves, and this is where I stop feeling like the moves are flowing nicely. In the game I played at 'a', but I had a feeling that was the wrong way to play. Incidentally I went on to lose this game by 1.5 moku. --BlueWyvern



BillSpight:

I think that B 2 is heavy.

[Diagram]
Diag.: Continuation (ii)

Considering that the Black stones in the bottom right corner are matched by 3 White stones (all marked), you can see that White's moyo there is small potatoes. Running with B 2 is not urgent, and gives White a target. Better to play somewhere like a, establishing a base on the right side and deepening Black's own moyo. Even better, I think, is to enlarge Black's moyo while attacking White's floating stones with a play like b. Maintain sente, and then go back and play at a. :-)

Later in the continuation diagram, the jump to B a is not bad, but you might consider this kind of development.


[Diagram]
Diag.: Inducing Move

B 1 splits White's stones, attacking both. If W 2 runs, B 3 becomes urgent. Black's idea is to make a good play (B 1), to evoke a response (W 2) that makes a nice play (B 3) better. This is an inducing move (called choshi in Japanese). Make your opponent make you make the play you want to make. :-)

Actually, W 2 does not look so great. How about something like this?


[Diagram]
Diag.: White attack

DaveSigaty: Wouldn't W prefer to play 'a' instead of 9 here? Going back to 1 in the next diagram seems very slow.

Bill: W 9 is played with an eye to the exchange, W 9 - B 10 in the following diagram (ii), and to the fact that, after B 10 in this digram, B 4 in diagram (ii) makes an empty triangle. But if White plans to play as in diagram (iii), the kosumi is indeed better than the sagari. :-)


[Diagram]
Diag.: White attack (ii)

As usual with contact fights, both sides are strengthened. That looks better for White than mutual running. :-)



Hmmm. W 5 looks like a mistake. How's this?

[Diagram]
Diag.: White attack (iii)


(Actually, in line with Dave's comments above, if White plans to play this way, she will not sagari on the right side, and the position will look like this:)

[Diagram]
Diag.: White attack (iiia)


Now it looks like Black's early nobi is a mistake. <sigh> How's this (ia)?

DaveSigaty: Instead of 7, won't W at 'a' capture the two B stones outright? Because the marked stone is there for support, B can't force his way out.

Bill: Yes, but then B b looks severe to me. So I thought W 7 was larger.

Dave: Yes, I think you are right. After B captures with 4 and 6 the center W stones look pretty pointless; but then W 9 seems to have little or no meaning.

Bill: Well, I was looking to Black's center stones and his weakness in the bottom left. But maybe White's center stones are too weak, especially considering White's weak group in the top left.

[Diagram]
Diag.: White attack (ia)

Black suffers a little bad shape, but keeps up the pressure on White. :-) What do you call B 1? Tsukiatari?



Of course, White can still cut.

[Diagram]
Diag.: White attack (ib)


[Diagram]
Diag.: White attack

DaveSigaty: What about this W 2? After the marked stone has been played, the original B stone has more the feeling of an invasion than an attack. I think B can be satisfied to reduce the side and escape. This reduces the value of the marked stone.

Bill: Dave, what are your thoughts if White stubbornly plays nidanbane at 5? White threatens to get pretty thick.

Dave: My original thought was the 6, 8 combo shown. However, I agree that W will end up thick in the outside. It is difficult to make something reasonable here. It shows the damage caused by exchanging the two marked stones since the black stone can not contribute anything to the situation.

Bill: Right.



Holigor:

[Diagram]
Diag.: Black 4?

It seems to me that the analysis shows that pehaps black 4 was a wrong decision. White is thick at the bottom so black can to better conecting his stones and supporting a stone that faces white's thickness. This gives white possibility to settle in the corner, but black will get thickness.

DaveSigaty: I still feel the main issue is B 2. This should be played in the top right at 'a' or one space above 5 (4 in the diagram below). W 3 is actually the wrong approach I believe and 4 is just the move to punish it. W 3 has no room to move after B 4. I think this should have been at 'b' or even something lighter like 'c'.


[Diagram]
Diag.: How about this 4?

Dave: I think that if W gets the chance to play something like 5 she is well off in this game. She is going to end up with only one weak group (upper left) and B looks like he will have a hard time competing on territory.



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