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Question of opening/reducing
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Author:  gostudent [ Tue Nov 25, 2014 9:35 pm ]
Post subject:  Question of opening/reducing

This is the opening of a recent game:

Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 6 . . . . . |
$$ | . . . 4 . . . . . 8 . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . b . . |
$$ | . . . a . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 2 . . . . . 9 . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


What should white play now? Should white take the big point near (a), or should white do some reducing? If white wants to reduce the bottom right, how should white do it?

Let say white plays at (a), and then black encloses the corner, leading to the following. What should white do next? If white wants to reduce the lower right now, what are some possibilities?

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


Thanks.

In the actual game, black made a mistake by playing a small move after I played at (a). So I still had a chance to reduce black in the lower right by playing a one-space high approach. I probably did it wrong in subsequent moves, though, as I failed to make any strong shape. I got away only because black decided to sacrifice the left-middle stone when I pincher at (b) later.

Author:  Solomon [ Wed Nov 26, 2014 11:05 am ]
Post subject:  Re: Question of opening/reducing

If I was Black and it was my turn, I would love to play here to expand my moyo:
Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . B . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . X . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


But it's White's turn, so by following the proverb that my enemy's key point is my key point, I would play here to expand my moyo:
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . W . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . X . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Is it the only move? No. But it's simple and effective.

Author:  Abyssinica [ Wed Nov 26, 2014 11:26 am ]
Post subject:  Re: Question of opening/reducing

Tenen may be too far; how about a 9-9 point?

Author:  skydyr [ Wed Nov 26, 2014 12:28 pm ]
Post subject:  Re: Question of opening/reducing

Abyssinica wrote:
Tenen may be too far; how about a 9-9 point?


Which one?

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


I think A is not quite as good, because black can easily take tengen anyways and leave white more cramped. B and D feel at least somewhat miai, white taking D to build or B to destroy, and black taking the other to do the same thing. C feels a little far, but that doesn't mean it's wrong. My gut instinct for C as compared to tengen is that it's more geared to turning the center into dame through fighting. It's more loosely connected to white's formation, so it becomes easier for black to invade, and being closer to black's strong position, it has less maneuvering room.

In any case, I feel the next big point is going to be in the vicinity of E, which will probably be sente or sente-ish for black.

Author:  Uberdude [ Wed Nov 26, 2014 2:26 pm ]
Post subject:  Re: Question of opening/reducing

Another plausible choice for white, if he feels territorial, is as below:

Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 6 . . . . . |
$$ | . . . 4 . . . . . 8 . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . b . . |
$$ | . . . a . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 2 . . . . . 9 . . . . . , . . . |
$$ | . . . . . . . 0 . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


To stop this, black will often approach the lower left rather than simply extending.

Click Here To Show Diagram Code
[go]$$Wm8
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . 1 . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . 4 . . . . . , . . . |
$$ | . . . . . 2 . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answering at 10 is a good simple choice, but white could also pincer to resist black's plan.

The downside of my suggestion is black can go for a moyo, but I don't fear that:

Click Here To Show Diagram Code
[go]$$Wm8
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . 1 . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . d . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . a . . . . . b . . . . . , . . . |
$$ | . . . . . . . . . . . . . . c . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . 4 . . . . . . . 6 . . . |
$$ | . . . O . . . . . 2 . e . . . , . . . |
$$ | . . . . . 5 . 3 . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


If black makes a shimari with 13 white could think about moves like a-e. Black might play 13 more ambitiously with something like below but white has plenty of things to aim at like a-d (notice c has attacking power):

Click Here To Show Diagram Code
[go]$$Wm8
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . 1 . 7 . . . X . . . |
$$ | . . . . . . . . . . . . 6 . . . . . . |
$$ | . . . . . . . . . . 8 . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . d . . . . . , . . . |
$$ | . . . . . . . . . . . . . . b . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . 4 . . . . . . . a . . . |
$$ | . . . O . . . . . 2 . c . . . , . . . |
$$ | . . . . . 5 . 3 . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  gostudent [ Wed Nov 26, 2014 10:59 pm ]
Post subject:  Re: Question of opening/reducing

Uberdude wrote:
Another plausible choice for white, if he feels territorial, is as below:

Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 6 . . . . . |
$$ | . . . 4 . . . . . 8 . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . b . . |
$$ | . . . a . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 2 . d . . . 9 . . . . . , . . . |
$$ | . . . . . c . 0 . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I am under the impression that three-space extension is often bad, because of the potential invasion of (c) or (d) (and in this case, that would also be corner approach). For the top right corner, I am not afraid because I have entering 3-3 as emergency option, but here I am less sure.

What should white do if black invades at (c) or (d)? Thanks.

Author:  EdLee [ Thu Nov 27, 2014 1:30 am ]
Post subject: 

gostudent wrote:
I am under the impression that three-space extension is often bad, ...
Hi GoStudent, you want to get rid of this kind of thinking immediately.
It all depends on the local and global contexts.

For example:
Quote:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 6 . . . . . |
$$ | . . . 4 ? ? ? ? ? 8 . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 7 . . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . , . . . . . , . . . . . , ? . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . . . . . . . . . . . . . . ? . . |
$$ | . . . 2 . . . . . 9 . . . . . , ? . . |
$$ | . . . . ? ? ? 0 . . ? ? ? ? ? 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

If you're worried about the gap between :w2: and :w10: ,
then what about the even bigger gap between :b9: and :b3: ?
Or between :b3: and :b5: ? Between :b5: and :b7: ?
Between :w4: and :w8: ?

Some ways to improve your understanding of these shapes:
play games, review them, and study the variations.
For example, you asked about B's invasion between :w2: and :w10: --
that's a good question. :)

Author:  Uberdude [ Thu Nov 27, 2014 3:47 am ]
Post subject:  Re: Question of opening/reducing

gostudent wrote:
I am under the impression that three-space extension is often bad, because of the potential invasion of (c) or (d) (and in this case, that would also be corner approach). For the top right corner, I am not afraid because I have entering 3-3 as emergency option, but here I am less sure.

What should white do if black invades at (c) or (d)? Thanks.


First of all, you should realize that while 10 is a 3 space extension, that is not its primary purpose; that is to undermine the 4th line black stone of 9.

Next is to appreciate the big difference between a 3 space extension from 3rd to 4th line and one from 3rd to 3rd or 4th to 4th. The former has much better connectivity, as shown in the diagram below. In the latter you can usually connect by attaching and sacrificing a stone, but that is costly.

Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . 8 6 . . . . . . . 8 6 . . . . |
$$ | . . . O 5 2 3 . . , . . . 5 2 3 . . . |
$$ | . . . . 7 1 4 O . . . . O 7 1 4 O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


The next important thing is the presence of the opponents stones, particularly as checking extensions. These make the invasion more difficult to deal with as they are a friendly stone for your opponent to connect to and mean you can't extend to make eyespace on the side.

So perhaps a better "proverb" would be:
Quote:
A 3 space extension on the 3rd line has poor connectivity, so if you want to be connected you should only do it if you have a good plan to deal with the invasion.


Let's look at some examples:

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . X . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . 2 . . |
$$ . . . . . . . . |
$$ . . . . , 1 . . |
$$ . . . . . . . . |
$$ . . . . . 4 . . |
$$ . . . . . . . . |
$$ . . . . . 3 . . |
$$ . . . . . . . . |
$$ . . . . , X . . |
$$ . . . X . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


Here white is in black's sphere of influence with a strong shimari below (black already has checking extensions both sides), so a 3 space extension is not a good idea as white doesn't want to make 2 groups but stay connected and settle his one stone. So a 2 space extension is better.

However here black has just a 4-4 below, so white's jump out is pretty much sente*, which then allows the kosumi of 7 to more-or-less connect (black could then play a which threatens to push at b and cut with black having the tesuji of c to make miai to connect above or below, so it is honte for white to answer a at b.

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . X . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . 2 . . |
$$ . . . . . . . . |
$$ . . . . , 1 . . |
$$ . . . . 7 . . . |
$$ . . . . b 4 c . |
$$ . . . . . . . . |
$$ . . . 5 . 3 . . |
$$ . . . . . . . . |
$$ . . . . X . a . |
$$ . . 6 . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


*If black doesn't answer white is happy to build influence on the lower side and later could save 1 or use its aji with e.g. z.

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . X . . . |
$$ . . . . . . . . |
$$ . . . . . z . . |
$$ . . . . . . . . |
$$ . . . . . 2 . . |
$$ . . . . . . . . |
$$ . . . . , 1 . . |
$$ . . . . 6 . . . |
$$ . . . . . 4 . . |
$$ . . . . . . . . |
$$ . . . 5 . 3 . . |
$$ . . . . . . . . |
$$ . a 7 . X . b . |
$$ . 9 8 0 . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


Sometimes we don't mind being disconnected as we have space to extend. Here white extends 3 spaces with 3 and if black invades just calmly makes a 2 space extension to settle the lower stone (note this is not a 3 space because we don't want to get split now, like above). Black might then follow up on 1 with a/b and white might continue there, or more likely at this stage of the opening, tenuki to a bigger area.

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . 2 . . . . . |
$$ . . . . X . . . |
$$ . . . . . a . . |
$$ . . . . b 1 . . |
$$ . . . . . . . . |
$$ . . . . . 4 . . |
$$ . . . . . . . . |
$$ . . . . , 3 . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . 5 . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . , X . . |
$$ . . . X . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


As a variation on the above, if black doesn't have a shimari at the bottom right white could think about making a 2nd 3 space (2 is still good and simple) though it could get rather crazy complicated. Simple is for black to answer with shimari and then white defends the gap.

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . 2 . . . . . |
$$ . . . . X . . . |
$$ . . . . . . . . |
$$ . . . . . 1 . . |
$$ . . . . . . . . |
$$ . . . . . 4 . . |
$$ . . . . . . . . |
$$ . . . . , 3 . . |
$$ . . . . . . . . |
$$ . . . . 7 . . . |
$$ . . . . . . . . |
$$ . . . . . 5 . . |
$$ . . . . . . . . |
$$ . . . 6 , X . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


Or things could go crazy. (I would only recommend doing this when you are dan level.)

Click Here To Show Diagram Code
[go]$$W
$$ ----------------+
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ . . 2 . . . . . |
$$ . . . . X . . . |
$$ . . . . . . . . |
$$ . . . . . 1 . . |
$$ . . . . . . . . |
$$ . . . . . 4 . . |
$$ . . . . . . . . |
$$ . . . . , 3 . . |
$$ . . . . . . . . |
$$ . . . . . 6 . . |
$$ . . . . . . . . |
$$ . . . . . 5 . . |
$$ . . . . . . . . |
$$ . . . . 7 X . . |
$$ . . . . 8 9 . . |
$$ . . . . . . . . |
$$ . . . . . . . . |
$$ ----------------+[/go]


As you say, another way to deal with the invasion is sacrificing one stone and using it to jump into 3-3. Now in your board if black invaded at the top white should probably attach on top as it's a 3rd to 4th line 2 space extension with good connectivity, but if k16 was at k17 then 3-3 makes more sense.

So back to your question, my first thought is to attach and stay connected. Black can wedge with 13 because he has the ladder (to top right if white ataris from below and connects to left). Black gets the corner, but white gets a strong wall that contributes to his growing left side moyo, and also k4 has become rather weak. I prefer white as black is ruining his own moyo prospects with giving white such thickness.

Click Here To Show Diagram Code
[go]$$Bm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . d . . . . . . . . . . . . . |
$$ | . . . . 4 . . . . . . . . . . . . . . |
$$ | . b 8 O 3 2 6 . . X . . . . . , . . . |
$$ | . 0 9 7 5 1 . O . . . . . . . X . . . |
$$ | . a . . . . c . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Another idea is to jump to the key point that black would like to have got and start a big running fight. But now white wants to play at a and b, so while might be able to play b and then cut at the waist if black a as black doesn't have the ladder, this is a complicated fight so I would recommend the simple attach of before.

Click Here To Show Diagram Code
[go]$$Bm11
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . . . . 5 . b . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . . . 3 . 2 . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . , . . . |
$$ | . . . . . 1 . O . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  Bill Spight [ Thu Nov 27, 2014 9:06 pm ]
Post subject:  Re: Question of opening/reducing

In a similar position Go Seigen commented on this line of play.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . O . . O . . X . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 6 . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . 5 . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 3 1 . . . |
$$ | . . . . . . . . . . . . . 4 2 . . . . |
$$ | . . . O . . . . . X . . . . . , . . . |
$$ | . . . . . . 7 . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White is not bad, he said. :)

Author:  gostudent [ Fri Nov 28, 2014 2:51 am ]
Post subject:  Re: Question of opening/reducing

Thank you for Uberdude detailed explanation, and Bill's suggestion of a possible reduction technique.

And thank you for EdLee's thoughts as well -- I would learn more when I consider specific stone settings, since the right answer differs depending on the setting.

Author:  Joelnelsonb [ Thu Dec 04, 2014 4:30 pm ]
Post subject:  Re: Question of opening/reducing

I'm certainly no expert but I can tell you that I once saw a Nick Sibbicky lesson where he states that if you're below 5 kyu then you shouldn't ever take the tengen unless its extremely obvious you should do so (such a blocking an atari or something) because beginners almost always play it at the wrong time. This being said, I would imagine that playing anywhere in the center at the given time of the example would be premature and ultimately pointless.

Author:  Solomon [ Fri Dec 05, 2014 5:17 pm ]
Post subject:  Re: Question of opening/reducing

Joelnelsonb wrote:
I'm certainly no expert but I can tell you that I once saw a Nick Sibbicky lesson where he states that if you're below 5 kyu then you shouldn't ever take the tengen unless its extremely obvious you should do so (such a blocking an atari or something) because beginners almost always play it at the wrong time. This being said, I would imagine that playing anywhere in the center at the given time of the example would be premature and ultimately pointless.

Judging the merit of a move off a rule of thumb dependent on the level of the player making the move is silly.

Author:  Abyssinica [ Fri Dec 05, 2014 8:16 pm ]
Post subject:  Re: Question of opening/reducing

Araban wrote:
Joelnelsonb wrote:
I'm certainly no expert but I can tell you that I once saw a Nick Sibbicky lesson where he states that if you're below 5 kyu then you shouldn't ever take the tengen unless its extremely obvious you should do so (such a blocking an atari or something) because beginners almost always play it at the wrong time. This being said, I would imagine that playing anywhere in the center at the given time of the example would be premature and ultimately pointless.

Judging the merit of a move off a rule of thumb dependent on the level of the player making the move is silly.



When a 15k plays a weird move, we assume he's just bad.

When a 9p plays that same weird move, we assume he's profound and knows much more about the game than we do.

Author:  EdLee [ Fri Dec 05, 2014 9:46 pm ]
Post subject: 

Abyssinica wrote:
When a 15k plays a weird move, we assume he's just bad.

When a 9p plays that same weird move, we assume he's profound and knows much more about the game than we do.
Yes. That's based on our experience and statistics.

If you jump off a tall building, experience and statistics tell us most likely you'll die. But there's some non-zero probability that some huge wind or a giant balloon may save your life.

Author:  illluck [ Sun Dec 07, 2014 10:49 pm ]
Post subject:  Re:

EdLee wrote:
Abyssinica wrote:
When a 15k plays a weird move, we assume he's just bad.

When a 9p plays that same weird move, we assume he's profound and knows much more about the game than we do.
Yes. That's based on our experience and statistics.

If you jump off a tall building, experience and statistics tell us most likely you'll die. But there's some non-zero probability that some huge wind or a giant balloon may save your life.


What.

Author:  skydyr [ Tue Dec 23, 2014 1:36 pm ]
Post subject:  Re: Question of opening/reducing

Abyssinica wrote:
When a 15k plays a weird move, we assume he's just bad.

When a 9p plays that same weird move, we assume he's profound and knows much more about the game than we do.

The move itself is almost irrelevant. It's the plan that matters, and the devil is always in the details.

I play 9p moves too, but I certainly haven't considered all the angles the way a professional would.

Author:  Unusedname [ Thu Dec 25, 2014 2:45 am ]
Post subject:  Re: Question of opening/reducing

Bill Spight wrote:
In a similar position Go Seigen commented on this line of play.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . O . . O . . X . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 6 . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . 5 . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 3 1 . . . |
$$ | . . . . . . . . . . . . . 4 2 . . . . |
$$ | . . . O . . . . . X . . . . . , . . . |
$$ | . . . . . . 7 . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White is not bad, he said. :)


This is cool. I'm gonna try to find a move like this in my next few games.

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