I dont understand this move

[entropi]

$$Wc
$$ ----------------
$$ | . . . . . . . .
$$ | . . . X . . . .
$$ | . . . . . X 1 .
$$ | . . . O . . . .
$$ | . . . . . . . .
$$ | . . O . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . O . . . .
$$ | . . . . . . . .

Click Here To Show Diagram Code

[go]$$Wc
$$ ----------------
$$ | . . . . . . . .
$$ | . . . X . . . .
$$ | . . . . . X 1 .
$$ | . . . O . . . .
$$ | . . . . . . . .
$$ | . . O . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . O . . . .
$$ | . . . . . . . .[/go]

I have seen this move a lot in high dan games, but fail to understand the merits of it.
I don't know if it's joseki, but it seems to violate every single "basic principle" I know, thus creating short circuits, stack overflows and deadlocks in my poor brain.

This move is neither and extension, nor an invasion, nor a reduction, nor a defense, ...

It looks like an attacking move, but then my question would be what happened to the principle "don't touch the weak stone when attacking"?

Maybe it's a probe. In this case, I would guess black is supposed to chose between the d18 stone and the top (towards the right side). But then I still don't see why this move is necessary for white. What prevents white from immediately taking either the corner or the top (i.e. without reinforcing black).

On top of that, how would white answer B-f16, which would be my first instict move?

Thanks in advance for eventual answers.

[EdLee]

what happened to the principle "don't touch the weak stone when attacking"?

1. There are no weak groups.
2. All principles, proverbs, and guidelines are exactly that -- they are merely general ideas; every situation is different and there are always exceptions.

[entropi]

what happened to the principle "don't touch the weak stone when attacking"?

1. There are no weak groups.
2. All principles, proverbs, and guidelines are exactly that -- they are merely general ideas; every situation is different and there are always exceptions.

1. Do you think f17-d18 stones are already strong enough? I am not sure about that. It is usual to attack such a group from the left side, isn't it? Of course black has the 3-3 option but that's the trade, black takes the corner white the top.

2. Of course, but there must be a reason for violating basic principles. This is precisely what I am asking

[EdLee]

1. Do you think f17-d18 stones are already strong enough?

Of course. There are no weak groups yet; and both B and W can play lightly.
And yes, it's joseki.

[mw42]

See http://www.gocommentary.com/free-videos ... go-07.html for some discussion on that move.

[Shaddy]

$$Wc
$$ ----------------
$$ | . . . . . . . .
$$ | . . . X . . . .
$$ | . . . . . X 1 .
$$ | . . . O . . . .
$$ | . . . . . . . .
$$ | . . O . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . O . . . .
$$ | . . . . . . . .

Click Here To Show Diagram Code

[go]$$Wc
$$ ----------------
$$ | . . . . . . . .
$$ | . . . X . . . .
$$ | . . . . . X 1 .
$$ | . . . O . . . .
$$ | . . . . . . . .
$$ | . . O . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . O . . . .
$$ | . . . . . . . .[/go]

I have seen this move a lot in high dan games, but fail to understand the merits of it.
I don't know if it's joseki, but it seems to violate every single "basic principle" I know, thus creating short circuits, stack overflows and deadlocks in my poor brain.

This move is neither and extension, nor an invasion, nor a reduction, nor a defense, ...

It looks like an attacking move, but then my question would be what happened to the principle "don't touch the weak stone when attacking"?

Maybe it's a probe. In this case, I would guess black is supposed to chose between the d18 stone and the top (towards the right side). But then I still don't see why this move is necessary for white. What prevents white from immediately taking either the corner or the top (i.e. without reinforcing black).

On top of that, how would white answer B-f16, which would be my first instict move?

Thanks in advance for eventual answers.

If you played f16, white hanes underneath at f18. Black's shape looks pretty ugly at this point. Joseki is g16, and g18 is ok if black has the ladder. I think this one is played when white wants to develop the top, but I've never tried it myself, so I can't talk in detail.

[entropi]

See http://www.gocommentary.com/free-videos ... go-07.html for some discussion on that move.

Thank you. But I cannot watch the video. It may be because of my companies firewall and/or because of the China firewall (as stated on the page). I will try again later.

1. Do you think f17-d18 stones are already strong enough?

Of course. There are no weak groups yet; and both B and W can play lightly.

But even if they are to be assumed strong, this still does not explain what whites move achieves. If the black group is considered strong, then this move is even less likely to have an attacking purpose. Anyway, maybe it's a kind of probe but is still highly mysterous to me.

And yes, it's joseki.

Yes, I have seen it is considered joseki (eidogo), which means that there must be a good explanation of it somewhere. I hope the video link of mw42 will work at home.

[gowan]

A number of variations are shown on this SL page: http://senseis.xmp.net/?44PointLowAppro ... lideAttach

[entropi]

If you played f16, white hanes underneath at f18. Black's shape looks pretty ugly at this point.

Yes, it looks obvious once you mention it

A number of variations are shown on this SL page: http://senseis.xmp.net/?44PointLowAppro ... lideAttach

Thank you very much this explains a lot.

[daniel_the_smith]

I'm late to the party, I know--

It's fairly common in pro play, it gets played a little less than 10% of the time. It looks like white usually has a position in the opposing corner when playing it:



I've heard Mr. Yang refer to this move as "switching direction".