Invading the corner

speedchase · **#21**

Joaz, if the 4,4 actually had zero presence in the corner, then playing the 3,3 would be an equal result

illluck · **#22**

Shaddy wrote:

In chinese, the verb used with the 3-3 invasion is dian3, which I don't think translates to 'invade'

That's one way to say it, though dian as a term in Go actually implies that it's a move inside. Another (less commonly used) term is just 3-3 入侵 (invasion).

bleep · **#23**

Many thanks to those who took what looks to be a lot of time for the diagrams! Now to internalise that...!

countsheep · **#24**

In most cases, when the two wings are the same length. 33 invasion would be a good choice. It's not about "early" or "late".
It as simply as, if a=b, go 33.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . X . . a . . . W . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ --------------------------------------- $$ {AR R15 R10} $$ {AR P17 K17} $$ {AR P17 Q17} $$ {AR R15 R16}[/go]

It's easy to understand. When you invade 33, the opponent has to choose between a and b. If you didn't have a stone at c, of course the opponent would block a. It's too easy for the opponent to make a choice, and after the joseki, b's efficiency is high.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . X . . . . . a W . . | $$ | . . . , . . . . . , . . . . . X b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , c . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

If the wings are not the same length, 33 is not a good choice. Black will definitely block b for a higher efficiency. Apparently, the right side is bigger.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . X . . . . . a W . . | $$ | . . . , . . . . . , . . . . . X b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In this diagram, the two wings are the same length. The opponent would be hard to make a choice. And, if the opponent blocks a(if block b, the result is the same),

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . X . . . . . a W . . | $$ | . . . , . . . . . , . . . . . X b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The circle marked stone is not efficient. That's an evidence why white's 33 invasion was a good choice. With an influence like this, black's two space extension is really slow. Black should extend further, or play somewhere else.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X O O . . | $$ | . . . . . . . . . X . . . X . X O . . | $$ | . . . , . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , B . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

That's it.

Here are two videos to learn corner techniques.
http://www.gocommentary.com/free-videos ... art-1.html
http://www.gocommentary.com/free-videos ... art-1.html

hyperpape · **#25**

Interesting perspective. But what about

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . W . . | $$ | . . . , . . . . . X . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

or

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . W . . | $$ | . . . , . . . . X , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

bleep · **#26**

So because you are forcing an inefficiency, that makes it a worthwhile play? It seems to me that this would only really start to affect your game at a much higher level than kyu level? Obviously, all the small inefficiencies will add up and result in a generally poorer standard of play, but don't you need to be able to take advantage of these inefficiencies in order to benefit? I wouldn't have a clue how to benefit from the diagram below!

Musing further, I suppose the benefit of the below is passive, in that you have 'wasted' a move of the opponents'?

countsheep wrote:

...

The circle marked stone is not efficient. That's an evidence why white's 33 invasion was a good choice. With an influence like this, black's two space extension is really slow. Black should extend further, or play somewhere else.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . X O O . . | $$ | . . . . . . . . . X . . . X . X O . . | $$ | . . . , . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , B . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

That's it.

Here are two videos to learn corner techniques.
http://www.gocommentary.com/free-videos ... art-1.html
http://www.gocommentary.com/free-videos ... art-1.html

countsheep · **#27**

hyperpape wrote:

Interesting perspective. But what about

In your diagrams, invading san-san is a good choice.

For the same reason, in the diagram below, invading 33 would be not good.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . W . . | $$ | . . . , . . . . . X . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The rule is applicable if the wing stone is on the point a-j.
Of course, we are talking about local. Sometimes we should think of the whole board.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . a c e g i . . . W . . | $$ | . . . , . . . . b d f h j . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Alguien · **#28**

bleep wrote:

So because you are forcing an inefficiency, that makes it a worthwhile play? It seems to me that this would only really start to affect your game at a much higher level than kyu level?

That (common) reasoning doesn't work in go. It's equivalent to playing for territory because influence is harder.

Go works on a system of equilibriums, if you bias one side for any reason other than the position on the board, you're forcing yourself to play worse than what's possible for you.

You may argue that it's worse in a way that will make it easier for you to win that game. But at the same time, that behaviour is self-feeding: you need to play for territory to win because you play worse because you play for territory to win even while knowing it's not the best move.

Forcing an inefficiency is objectively good. If it doesn't give you an advantage you can either change that fact and advance or not force the inefficiency and enter the self feeding loop.

Phelan · **#29**

bleep wrote:

So because you are forcing an inefficiency, that makes it a worthwhile play?

I think that is partly it, but also that you get to play there before the opponent. If you let him play there, the corner gets settled, and becomes huge.

In the cases where the distance is not the same, however, there is usually a better invasion/reduction than just playing 3-3.
At least, that's what I think people were meaning.

Uberdude · **#30**

bleep wrote:

Obviously, all the small inefficiencies will add up and result in a generally poorer standard of play, but don't you need to be able to take advantage of these inefficiencies in order to benefit? I wouldn't have a clue how to benefit from the diagram below!

Musing further, I suppose the benefit of the below is passive, in that you have 'wasted' a move of the opponents'?

Right, the inefficiency is already a good result for you. They aren't something you need to find a follow-up for to take advantage, you already have one. The way this is manifest is by counting at the end of the game. As you both played the same number of moves (assuming you don't bizarrely start passing in the middle of the game) then if your stones are more efficient then you will have more territory and win.

speedchase · **#31**

countsheep wrote:

hyperpape wrote:

Interesting perspective. But what about

In your diagrams, invading san-san is a good choice.

no it isn't. especially not in the last one.

countsheep · **#32**

Uberdude wrote:

Right, the inefficiency is already a good result for you. They aren't something you need to find a follow-up for to take advantage, you already have one.

Yes, I agree with you. Go is a zero-sum game, it's all about efficiency. If you have a higher efficiency, the territory comes with you. And that's why people like the good shapes and hate the bad ones.

speedchase wrote:

no it isn't. especially not in the last one.

I said 33 invasion is a good choice, but I don't mean it's the only choice. And, I said it's all about local.
Let's just talk about the last diagram. Maybe you think white should kakari and play like this. What do you think about this diagram?

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . a O . . W X . . . . | $$ | . . . , . . . . X , . . . W . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Actually, locally the result is bad for white. We all know, with the two circle marked stones, w should extend a. But in this diagram white can only play a two space extension. So white is an inefficient shape.
Why so many people play this diagram? That's because, white wanted to break black's moyo, or the moyo in potential. With the white group on the top, black can't make a moyo. That's the whole board thinking. It means the diagram is locally bad, but maybe globally good.
So, locally, 33 is still a good choice. But if you are worried about the moyo, you can kakari and play the diagram above.

Invading the corner

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