In my games, pincers are times that make me feel even more clueless than I feel during most other parts of the game. So basically I have questions from both sides - when someone makes an approach, how do you know whether it's a good idea to pincer or to extend away from the approach? If you get pincered, how do you know whether you should run into the center or dive into the corner? Obviously for my level just some basic ideas would be great, or if there is any good treatment of this in the common Go books? Any recommendations on where to look would also be really great. Thanks!

Given your DDK level, here are a couple of rules of thumb, which you can apply unless you think you shouldn't. Go has many rules of thumb that have many exceptions. Don't worry about the complexity. Just violate a rule of thumb if you want to. You may be right.

The following rules of thumb are based upon go history, the accumulated wisdom of experience over centuries of play. They are also based, in part, upon the example of AlphaGo, who may know something no human does.

The first rule of thumb is when you are pincered, don't panic. If you approach a corner and your opponent pincers, you have prevented an enclosure with sente. Pat yourself on the back and play somewhere else, if you want to. If your opponent attacks your lonesome stone, you may be able to sacrifice it and play somewhere else again.

So the first thing to think about when pincered is to play somewhere else. Top players had figured this out centuries ago.

The second thing to think about is jumping out. Why? Because by doing so you may threaten the opponent's stone in the corner or the pincering stone. You are not just running out. Just running in order to run is in general a bad idea, something that top players also knew long ago.

The third thing to think about is playing to make life or a base. The base may not be alive without running, but that may be better than nothing.

Edit: Oh, yes, something I forgot to mention. I don't know where to put this idea, whether it is more important than making a base or not, but it is definitely something to think about, and that is to make a counter pincer. Typically your opponent will attack the pincered stone and then you can extend from your counter pincer. This is a common pattern of play.

To pincer or not to pincer, that is the question.

Centuries ago, when other top players ignored their pincers, top players figured out that not pincering, but playing somewhere else might be better. So the first thing to think about instead of pincering is to play somewhere else, if you want to.

Now, remember the second rule of thumb for the pincered stone, to jump out, threatening either side. That leads us to the second rule of thumb for whether to pincer. Think about extending from the corner instead. AlphaGo does that a lot. If you do that and then pincer, the pincered stone cannot jump out and threaten either side, because you have already strengthened one of the sides. You are not just strengthening the corner in order to make territory or to make a base, but to threaten a pincer. AlphaGo frequently replies in the corner and then follows up with a pincer.

Edit: Extending from the corner prevents a counter pincer, as well.

Sometimes an unsupported pincer is right, but it is the third thing to think about.

Good luck!

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One way to decide wether you want to pincer is to ask yourself wether you want more stones on the side where the pincer will be and wether the pincer stone does anything interesting or has any future.

For instance in the two following diagrams (shamelessly taken from an article by Takagawa Kaku 9p entitled 'All about the pincer' in Go World 5), is it interesting for black to add a stone on the upper side?

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . W . . . . . . O . . . . |
$$ | . . W , W . . . . , . 1 . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . . . . . . . . . . . . . . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$[/go]

According to Takagawa, " isn't worth much as a pincer". he doesn't go into great details but I'd say that the presence of a strong White position (the marked stones) on the upper side means that after the exchange of 2-3, black stone is definitely weaker than the two white stones (and it is white's turn). The pincer stone doesn't have much space to make a base and it may become a burden for black.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . O X . . . . . . . . . . . . . . |
$$ | . O . O O X . . . . . 1 . O . . . . . |
$$ | . O O X X . X . . , . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$[/go]

In this diagram on the other hand, Black has a strong position on the upper side so he can aim at building something here. His strength also means that he doesn't have to fear anything about the safety of the pincer stone, that's why Takagawa recommends to play .

In the same position, if black plays , " limits the effectiveness of the thickness that black has taken such pains to construct in the top left corner".

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . O X . . . . . . . . . . . . . . |
$$ | . O . O O X . . . . 2 . . O . . . . . |
$$ | . O O X X . X . . , . . . . . X . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$[/go]

Thank you both - this is great stuff to think about. Shenoute - in that second diagram, I can see how that ends badly for white. So does that mean the approach should probably be from the other side? Or is that even worse because black gets to extend and start mapping out a pretty big framework?

I guess that will depend a lot on the position on the right side but, yes, it might be better in some cases (especially if white has some potential on the right side).

Hi mvk20,

It's very nice to ponder and study these general ideas and theories (e.g. post 2), and specific positions (e.g. post 3). It's also good to actually play and review ( and review the reviews! ). You'll encounter some successes and horrible deaths -- both as the pincerer and the pincered. These direct experiences are very useful for this process.

( In addition to Bill's sample list of options -- tenuki, jump out, make life, counter-pincer -- there are also other available strategies and techniques such as attach (leaning), attach+hane, attach+cross-cut, armpit hit, shoulder hit, etc., and as always it depends on the exact whole-board situation; so we're back to play and review. )