Here is a position from one of my games, with the last 10 moves marked out. I played Black.
My question is how to analyze the board, and what areas 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.
You know, Black 2 is a good play. But after allowing White 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:
Now if White replies at a I'll be happy to play at b. ;-)
Is Black 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?
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 White to connect underneath has seriously weakened Black while expanding White's territory. The marked black stones are essentially worthless now and the natural fate should be to end up captured by White (Black should be interested in how to get White to spend time capturing them on a small scale).
- Lower Left Corner - White has about 15 points of solid territory. I agree with Bill that Black has unfortunately let White off easily here.
- Lower Side - The fact that White is strong in both corners means that the two black stones on the lower side are thin and subject to attack. White should have in mind that if she can somehow limit Black's prospects on the upper side in sente and play first here, she can reasonable expect to end up 50 points ahead of Black on the lower half of the board by expanding her territory while attacking Black. 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 :-), Black owns the upper half. However, thus far Black has nothing like the solid territory that White has claimed down below.
- Upper Left Corner - The black four-stone group in the upper left is very solid and has about 10 points of territory. The black three-stone group to the left is also very solid but should be counted as only 4-5 points of territory. The white formation is very interesting for Black and quite threatening for White because it has no base. Black would very much like to attack this group. There is no real prospect of catching it. However, Black 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 - Black 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 White's strong but low stone in the Lower Right. This stone is fairly distant, however, so Black still retains good overall potential in the upper right. Black is waiting now for White 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 white group floating in the upper left - White isn't home free yet.
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
I think that Black 2 is heavy.
Considering that the black stones in the bottom right corner are matched by three white stones (all marked), you can see that White's moyo there is small potatoes. Running with Black 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 Black a is not bad, but you might consider this kind of development.
splits White's stones, attacking both. If runs, becomes urgent. Black's idea is to make a good play (), to evoke a response () that makes a nice play () better. This is an inducing move (called choshi in Japanese). Make your opponent make you make the play you want to make. :-)
Actually, does not look so great. How about something like this?
DaveSigaty: Wouldn't White prefer to play a instead of here? Going back to in the next diagram seems very slow.
Bill: is played with an eye to the exchange, - in the following diagram (ii), and to the fact that, after in this digram, in diagram (ii) makes an empty triangle. But if White plans to play as in diagram (iii), the diagonal is indeed better than the descent. :-)
As usual with contact fights, both sides are strengthened. That looks better for White than mutual running. :-)
Hmmm. looks like a mistake. How's this?
(Actually, in line with Dave's comments above, if White plans to play this way, she will not play descent on the right side, and the position will look like this:)
Now it looks like Black's early nobi is a mistake. <sigh> How's this (ia)?
DaveSigaty: Instead of , won't White at a capture the two black stones outright? Because the marked stone is there for support, Black can't force his way out.
Bill: Yes, but then Black b looks severe to me. So I thought was larger.
Dave: Yes, I think you are right. After Black captures with and the center white stones look pretty pointless; but then 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.
Black suffers a little bad shape, but keeps up the pressure on White. :-) What do you call ? Tsukiatari?
Of course, White can still cut.
DaveSigaty: What about this ? After the marked stone has been played, the original black stone has more the feeling of an invasion than an attack. I think Black 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 ? White threatens to get pretty thick.
Dave: My original thought was the , combo shown. However, I agree that White 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.
It seems to me that the analysis shows that pehaps was a wrong decision. White is thick at the bottom so Black can do better connecting his stones and supporting a stone that faces white's thickness. This gives White the possibility to settle in the corner, but Black will get thickness.
DaveSigaty: I still feel the main issue is . This should be played in the top right at a or one space above ( in the diagram below). is actually the wrong approach, I believe, and is just the move to punish it. has no room to move after . I think this should have been at b or even something lighter like c.
Dave: I think that if White gets the chance to play something like she is well off in this game. She is going to end up with only one weak group (upper left) and Black looks like he will have a hard time competing on territory.