Life In 19x19

If you were in this position, what would you play? I've always played A, and I'm wondering what the merits of it are. As far as I know, it pushes above white's junction line as well as possibly defends against h3 and discourages the high approach on the right. I've also always considered B and C, but I have no clue what is the better of the moves, or if there's an alternative to these three.

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My first thought would be to invade at C17. White has made a symmetrical position radiating out from the upper left. The invasion is very big and forces White to choose which side to defend on. Normally Black can anticipate ending in sente and therefore getting to play first between the two moyos anyway.

ez4u wrote:My first thought would be to invade at C17. White has made a symmetrical position radiating out from the upper left. The invasion is very big and forces White to choose which side to defend on. Normally Black can anticipate ending in sente and therefore getting to play first between the two moyos anyway.

I also considered this, but I felt that white might do some variation to get sente or the double hane, and I think I'd have to protect the ponnuki I get out of that.

Here is a heuristic you can use to compare such plays. It is not so good if one of the plays is sente, but that is not the case here.

Assume that one player gets one of the plays (or in the vicinity) and the other player gets the other (or in its vicinity). That is, treat the two plays like miai. Then compare that position to the one that is the other way around. Which do you prefer?

If the two plays were equivalent miai, you would not prefer either, but if they are not equivalent, then this comparison should help you see which is better.

In this case in the top right the two players will not play on the some point, so it is a good example of the idea.

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[go]$$c This way?
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Click Here To Show Diagram Code

[go]$$c Or this way?
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You can also make comparisons with a play in the center. A center play is certainly playable in this type of position.

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[go]$$c Off center
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is a thought, as relating better to the Black stones on the third line that tengen would. FWIW, it forms a square with the marked stones. (Tengen might be a better move for White. )

P9 the normal continuation for the chinese opening if white doesn't reduce it first.
It will increase the lower side moyo considerably and reduce the chance of white invading the lower right corner.
Also it will protect the weakness around R12 a little bit and afterwards b becomes a good follow up.

White may gain sente but both of whites corners are still open while the lower side of blacks territory becomes really secure. My instinct tells me the position would be then good for black.

Abyssinica wrote:I also considered this, but I felt...

C17 was also my first feeling. Maybe your experience gave you different feelings about it.
So what are you going to do about it?

EdLee wrote:

Abyssinica wrote:I also considered this, but I felt...

C17 was also my first feeling. Maybe your experience gave you different feelings about it.
So what are you going to do about it?

I considered leaving c17 availible and either: 1.Getting it when it becomes big enough or 2.Getting free sente. Obviously the later I wait the less #2 is worth. Now I know that the normal 3-3 joseki leads to sente for the invader, but I thought the person I was playing (Who is 3k and is overly agressive ) [Also this is where the question arises since I have seen this situation more than once], would pick some variation where the invader ends in gote, or double hane. I know the double hane variation leads to a ponnuki for black, but I always feel I cannot tenuki away from that ponnuki. I feel it needs to have a defending move since it's behind enemy lines.

♫ Feelings ♫

What about P4 on the premise that white cannot finish the top left in one move? I forget what the specifics of P4 were though.

Loons wrote:What about P4 on the premise that white cannot finish the top left in one move?

P4 kosumi looks funny to me.

Abs, what's wrong with a ponnuki and defending it ?

I think your move in the game was alright. It isn't a move I can say for sure is wrong, but it does seem like it is impacting black's formation as a whole. So, I consulted my Chinese Opening book and it looks like Kato Masao can suggest a better course of action.

In Kato Masao's book on the Chinese Opening he says that the move before this one is when white needs to reduce black in the lower right immediately. He says the situation is urgent. Your opponent apparently disagreed with the 9 dan professional on this matter. Kato recommends a, b, or c to reduce the formation from the fifth line.

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[go]$$c Chinese Variation - Kato recommendations
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Considering that white ignored the urgency of the lower right, I'd recommend that you defend the lower right in a fashion consistent with the principles of the Chinese Opening (so not a direct enclosure).

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[go]$$c My recommended move for this situation
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The Low Chinese is all about provoking your opponent to play an unfavorable approach to the 3-4 stone. This move still leaves that as an option, but would make the resulting approach move very painful. You could also play at 'a', but I don't like the double 3-space relationship it forms on the bottom.

I think the suggested move at 'b' is also possible. It does help the lower right, but it does little against the first two reduction moves that Kato Masao recommends against this formation. For this reason I chose the marked stone.

Loons suggested something similar in this part of the board. I think the kosumi at 'c' is also playable, but it doesn't do a great job of defending weaknesses in the bottom nor does it offer to have black build on as large of a scale if black is able to get the move at 'b'. Still, I can't really disagree with the move since it does defend the urgent part of the board.

Technically it's the Low chinese + Kobayashi, and the normal move against the kobayashi probably still fits within the trap that the low chinese is trying to create. No one has mentioned Kobayashi yet, so that makes me curious.

Abyssinica wrote:Technically it's the Low chinese + Kobayashi, and the normal move against the kobayashi probably still fits within the trap that the low chinese is trying to create. No one has mentioned Kobayashi yet, so that makes me curious.

It seems to me the bottom right Chinese enclosure must be more interesting, since it has a defended friendly corner above it and a kobayashi left of it, while the kobayashi has white left of it.

Notwithstanding I think this board is usually reached from Chinese.

Abyssinica wrote:Technically it's the Low chinese + Kobayashi, and the normal move against the kobayashi probably still fits within the trap that the low chinese is trying to create. No one has mentioned Kobayashi yet, so that makes me curious.

Well, there are a few reasons for that. First, the Low Chinese is older so this variation was being played before Kobayashi popularized his namesake fuseki. Second, as Loons said, the position is usually reached from the Low Chinese - normally white would just approach the Kobayashi corner with the two-space low right after the formation is made. Third, I didn't even consider the fact that this was a Kobayashi formation until you mentioned it.

But I do find this interesting. Both the Kobayashi and Chinese fuseki center around trying to get your opponent to approach your corner so you can attack the approach stone. The trick with the Kobayashi is not to play a standard approach move as you will be severely attacked thanks to the influence from the star point stone. The trick with the Chinese formation is that you can't approach too soon or your opponent will get too much compensation.

So I think that is why Kato Masao says the lower right is so urgent for white to do something about in this situation - even if he wasn't thinking about the Kobayashi aspect directly. You have this combination of two openings that focus on how the lower right will be played. The first player to get a move there will clearly have an advantage as they get to dictate the flow in this part of the board.