Hi all!

[Chew Terr]

White plays the 4-4 saying 'I want to build stone shapes in this area'. Black is saying 'Not in this direction, you don't.

When I said attack, I do not mean to kill. I mean restricting white's options. If white lets you keep coming back to the area, you might restrict one direction at a time until he has nowhere to run, but that's not really the intent. It halfway forces white to either go the opposite direction or pincer, which is fighting to struggle in that restricted direction. Both can turn out perfectly fine for both players. By approaching the corner, you are hoping to get either the corner or a piece of the side you approach from (if not some of both). So attack may not be as good a term, as 'approach'. Black is hoping that something like this happens.

$$B common response
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . 4 . . 1 . . 5 . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |

Click Here To Show Diagram Code

[go]$$B common response
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . 4 . . 1 . . 5 . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

You see, neither player really got that much of the corner, but both got fairly solid shapes that give them a stake on one side or the other. Black is particularly happy because this solid shape complements his top right stone, helping him build a loose network across the whole top. White can certainly invade or approach, but black is going to get something out of it, since he's so well positioned. There may be better responses, but this sort of setup happens a lot.

[Harleqin]

How does the black stone attack the white one? It is not in contact; it just prevents a white extension, doesn't it?

The most important rule in Go is:

Each player can play at most one stone on his turn.

In this situation, the black stone has 4 liberties:

$$
$$ . . . . . .
$$ . . . . . .
$$ . . X . . .
$$ . . . . . .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$
$$ . . . . . .
$$ . . . . . .
$$ . . X . . .
$$ . . . . . .
$$ . . . . . .[/go]

If now White plays here:

$$W
$$ . . . . . .
$$ . . . . . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . .
$$ . . . . . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .[/go]

is this an attack? Please remember that it is Black's move now.

Answer:

No, it is not. Depending on the surroundings, Black will answer by either stretching or bending:

$$W
$$ . . . . . .
$$ . . 2 . . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . .
$$ . . 2 . . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .[/go]

After the extension, the black group has 5 liberties, while the white stone has only 3. This is a simple, but effective way to play.

$$W
$$ . . . . . .
$$ . . . 2 . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . .
$$ . . . 2 . .
$$ . . X 1 . .
$$ . . . . . .
$$ . . . . . .[/go]

After bending, the white stone has only 2 liberties, but the black stones have 3 each. This is more complicated, because there is now a cut between the black stones. White will now most often have to extend his stone in turn; bending or cutting directly are techniques for special situations. After White has moved, it is Black's turn again, so he gets to protect the cut.

So you see, Black actually gets stronger when White attaches.

If you explore the above mentioned rule (each player can play at most one stone on his turn), you will see that setting up a single big continuation just lets the opponent take that away. The trick in Go is to play in such a way that more big continuations are available of which the opponent can take only one on his next move. This works in a mutual fashion, and very often, the opponent's point is your own (meaning that you and the opponent want to play the same point).

Now, what kind of moves do we want to play? Mostly, this means extending one's own stones or taking an extension from the opponent's. We build loose frameworks on a large scale, which then get invaded or tightened on a smaller scale, and finally sometimes transformed into territory. However, the larger scale is based on knowledge of the smaller scale, so it makes sense to first mainly explore the basic stone interactions on a small board, then turn to gradually bigger ones.

[Violence]

I know this may sound biased coming from someone with a screenname like mine, but...

Your strength will increase proportionally to your ability to read and fight. Especially for beginners, I recommend doing a good amount of stone capturing problems and just getting good at capturing.

[Elesthor]

I think i've understand what you mean!

So, my aim in an attack isn't actually to kill the stone(s) I approach, but to reduce my opponent's choices and possibilities (like extensions,...). It is both an attack move and a defensive one (preventing from an extension too).


@ Violence: I am making Life and death's Tsumegos almost everyday =)

[Chew Terr]

Sounds like you're grokking this way faster than I ever did . Great job, let us know if you have any other questions. Yeah, I really ought to do more L+D...

[Elesthor]

Thx, but it is with your help

[Elesthor]

After playing a few games versus gnuGo, I was wondering wether it is more important to try to make the biggest center moyo, or to make side's moyo 'safer' ?

Another question, is this extension a good one?

$$
$$ . . . . . .
$$ . X . . . .
$$ . . . . X .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$
$$ . . . . . .
$$ . X . . . .
$$ . . . . X .
$$ . . . . . .[/go]

It doesn't look very solid...

Thx

[Chew Terr]

From a corner? Yes, it is perfectly reasonable. Beware, it is not bulletproof or good in all cases, but it covers enough ground that it is perfectly good for a lot of situations. For example, if the side is important enough to risk, for example, some attack on your corner. There's not a huge weakness here, but it's worth noting. This move is definitely faster than something like a knight's move enclosure, but slower than, say, just jumping to the middle star point.

[Harleqin]

It depends. On an empty board, almost any two stones form a good shape.

[xed_over]

After playing a few games versus gnuGo, I was wondering wether it is more important to try to make the biggest center moyo, or to make side's moyo 'safer' ?

Generally, the proverb goes like this: Corners are golden, sides are silver, the center is straw (or something close to that, anyway)

Another proverb says: There's no territory in the center

Another question, is this extension a good one?

$$
$$ . . . . . .
$$ . X . . . .
$$ . . . . X .
$$ . . . . . .

Click Here To Show Diagram Code

[go]$$
$$ . . . . . .
$$ . X . . . .
$$ . . . . X .
$$ . . . . . .[/go]

It doesn't look very solid...

Thx

this shape is known as a Large Knight's move
http://senseis.xmp.net/?LargeKnightsMove