Posts: 598 Location: Germany, Berlin Liked others: 333 Was liked: 102
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Just looking at it I'd say B is the only move.
edit: Forgot to tell why: A) Gives white to much forcing moves. Don't like the shape. B) More liberties. Puts severe pressure on the bottom left stones. Reserving which side to atari from seems good.
Last edited by p2501 on Fri Dec 14, 2012 6:39 am, edited 1 time in total.
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My reasoning: - the bottom b group has 3 libs. - the one next to it has also 3 libs. - whoever starts removing libs wins, if he can keep removing them. - can I pull off putting a stone on the point under B, to remove a lib from W? - I read it as a yes: - option 1: w ataris my stone, I extend to 'B', he extends to not die, I capture bottom. - option 2: w extends bottom, I play 'A' and capture w on a net (or he tries to escape net and I kill the now three stone bottom group).
(paint your problem as a usual (go) diagram and I'll paint my moves on it, if you want) [edit: ok, ok ,I'll paint it:]
[go]$$Bc If White resists, he just gets a weak group. B is save. $$ . . . . . . . . . . . . . . | $$ . . . . , . . . . . , . . . | $$ . . . . X . . . . . . . . . | $$ . . . . . . . . . . . B . . | $$ . . . . . . . . . . . . . . | $$ . . . . . . . . a . . . . . | $$ . . . . . . . . Q X X X X . | $$ . . . . , . X X Q X O O O . | $$ . . . . . . . @ X O O . O . | $$ . . . . . . b @ X X . O . . | $$ . . . . . . . . . . . . . . | $$ ----------------------------[/go]
White has two groups of cutting stones. Looks to me like move B makes miai out of a and b, and one of the groups is going to die.
Move A drives the triangle group over your own cutting stone, and forces its capture, but Black gets guaranteed influence. If playing B and capturing the low group is unsatisfying, then okay, play A. But that's basically 5th line territory that you're giving up. Not seeing the rest of the board, I think it's clearly better to fight to kill one of the two white groups.
Posts: 6727 Location: Cambridge, UK Liked others: 436 Was liked: 3720
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KGS: Uberdude 4d
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I don't know the answer to that problem, though probably A is best as they both work and A asks white to make a heavy group in bad shape before capturing the side stones, whereas if white gets to nobi there his shape is better and the black group to the right could be attacked.
Also in that sort of shape sometimes the m2 clamp is the only move fast enough.
P.S. In topazg's diagram although black captures the outside stones which is great white does have a 1st line connection for later which he doesn't with the atari. If black is trying to make territory to the left side that could be quite significant.
[go]$$Bc $$ . , . . . . . , . . . | $$ . X . . . . . . . . . | $$ . . . . . . . . X . . | $$ . . . . . . . . . . . | $$ . . . . X X . . . . . | $$ . . . X . . X X X X . | $$ . , . X X . X O O O . | $$ . . . . O X O O . O . | $$ . . . . O X X O O . . | $$ . . . . . O O . . . . | $$ ----------------------+[/go]
[go]$$Bc $$ . . . . . . . . . . . | $$ . , . . . . . , . . . | $$ . X . . . . . . . . . | $$ . . . . . . . . X . . | $$ . . . . . . . . . . . | $$ . . . . . . . . . . . | $$ . . . . . O X X X X . | $$ . , . 1 X O X O O O . | $$ . . . . O X O O . O . | $$ . . . . O X X . O . . | $$ . . . . . . . . . . . | $$ ----------------------[/go]
For a while I thought that might be the preferable way to capture (on an otherwise empty board), because the side is bigger than either the corner or center.
[go]$$Wc $$ . , . . . . . , . . . | $$ . X . . . . . . . . . | $$ . . . . . . . . X . . | $$ . . . . . . . . . . . | $$ . . . . . B . . . . . | $$ . . . 3 1 O X X X X . | $$ . , . 2 X O X O O O . | $$ . . . . O X O O . O . | $$ . . . . O X X . O . . | $$ . . . . . . . . . . . | $$ ----------------------+[/go]
What I don't get is if you're going to do this, why exchange the marked stone for ? Why not directly?
This line gets complicated. There is a white group cutting 3 black groups, only one of which is strong. I am having trouble seeing why capturing some white stones, connecting your groups, and leaving white with the only weak group isn't clearly right. Yet überdude also likes this move, so there has to be merit to this move that I'm not understanding. Can you explain it?
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Depending on the rest of the board, the clamp can also be a viable option if you really don't want white to connect his left side stones to the right side.
[go]$$Wc $$ . , . . . . . , . . . | $$ . X . . . . . . . . . | $$ . . . . . . . . X . . | $$ . . . . . . . . . . . | $$ . . . . . B . . . . . | $$ . . . 3 1 O X X X X . | $$ . , . 2 X O X O O O . | $$ . . . . O X O O . O . | $$ . . . . O X X . O . . | $$ . . . . . . . . . . . | $$ ----------------------+[/go]
What I don't get is if you're going to do this, why exchange the marked stone for ? Why not directly?
This line gets complicated. There is a white group cutting 3 black groups, only one of which is strong. I am having trouble seeing why capturing some white stones, connecting your groups, and leaving white with the only weak group isn't clearly right. Yet überdude also likes this move, so there has to be merit to this move that I'm not understanding. Can you explain it?
[go]$$Wc $$ . , . . . . . , . . . | $$ . X . . . . . . . . . | $$ . . . . . . . . X . . | $$ . . . . . . . . . . . | $$ . . . . . B . . . . . | $$ . . . 3 1 O X X X X . | $$ . , . 2 X O X O O O . | $$ . . . 4 O X O O . O . | $$ . . . . O X X . O . . | $$ . . . . . . . . . . . | $$ ----------------------+[/go]
In that case black plays here now and white doesn't have any particularly good move.
Playing the atari first wins hands down in this case. It's simply better technique.
That's because it creates better shape after capturing the stones, because makes white heavy before 'defending', because it slows white's future development and because it still creates miai. However, the answer to this question can change depending on the position. That's Go for you .
Here are some less settled (fictitious) positions to illustrate these points more clearly. Assume the ladder favors black in all cases.
Black has gained a little extra time to move here, because of the exchange of 1 for 2. If 6 is at 'e', black still plays 7. [Updated and fixed mistake where I kept saying white instead of black. Thanks friendly editor ]
(note: 5 is better than 'a' for fighting here. Play 5 when you expect fighting in the center. Now 'b' isn't sente, but 'c' is sente instead and 'd' is sente in either case.)
Now 'a' and 'b' are miai for black and white's too thin to fight like this. Note that if white cuts at 'a' and black extends to 'b', white's cutting stones are captured. However, if black had played 'c' instead of 5 earlier, white would be able to escape with 'd' and black would be in trouble. This illustrates the subtle difference between those two moves. A lot of people think 5 looks less stylish, but it's the fighting move.
Sacrificing 1 costs black something and strengthens white's four stone group (which has to be considered because it diminishes the value of separating white in the first place). However, it can't be denied that white's groups have been separated and white will have to make four eyes instead of two now. Black's shape is worse now too.
This is a fighting variation which can be good if the global position supports this sort of strategy.
White can play a makeshift defense with 4, then play 6, and black practically collapses. All black can do now is try desperately to recover with a squeeze at 'a'. It might be good enough to keep playing for awhile, but it doesn't really work well enough. Black lost a lot here.
Posts: 6727 Location: Cambridge, UK Liked others: 436 Was liked: 3720
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peppernut wrote:
Yet überdude also likes this move, so there has to be merit to this move that I'm not understanding. Can you explain it?
Pretty much exactly what David said; I was too lazy to make diagrams. The key points are 1) If you capture the stones in a ladder the nobi becomes a wasted move, so atari first is a kind of probe asking if white wants to let you capture more stones in a ladder which is obviously much better. 2) If white gets to nobi his shape is better and he gets out faster, David's 2a/2b is a nice example of this 3) Stop the first line connection.
P.S. for David: throw in at 6 in 1a could be a mistake and direct atari may be better: if black is going to tenuki the 1st line atari after the throw-in (which is usually the case) then the throw in reduces the yose value of taking the 3 stones as black can recapture so unless taking that black eye is strategically valuable the throw-in loses points (but is a very natural instinct I have to fight!).
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Uberdude wrote:
P.S. for David: throw in at 6 in 1a could be a mistake and direct atari may be better: if black is going to tenuki the 1st line atari after the throw-in (which is usually the case) then the throw in reduces the yose value of taking the 3 stones as black can recapture so unless taking that black eye is strategically valuable the throw-in loses points (but is a very natural instinct I have to fight!).
Yea, I hesitated on that move too, when making the diagram. Without seeing the rest of the board it's hard to say for sure. However I feel that if I were white I'd choose to play the throw in here, because it indirectly strengthens the pincer stone at Q10, which black is probably about to turn to attacking with sente (either way).
To be honest, I think that this sort of variation should hardly ever happen anyway, amongst strong players, because black becomes too thick if he plays well (I meant to say that earlier). Both players have to make several mistakes to reach that position under normal circumstances, but if it gets there, white still has more scope to hang tough when black plays the extension.
In this case I feel white can afford to pay a few points locally to remove the half eye, because she can gain more than that back on the right side with the leverage it creates, but I tend to be the kind of player who favors keeping positions unsettled for as long as possible, at the expense of hard cash. Think WWSD - what would Seo (Bongsu) do?
Also, the throw in better demonstrates how inferior black's shape is with the extension, for the sake of that example. I definitely agree that the throw in would be a mistake in the examples where where black captures three stones, because it achieves less than nothing in those cases.
Anyway, I can't say one is better than the other for sure here. Maybe a stronger player could, but I guess that's why we have the notion of style. Everyone weights the balance between territory and future attacking potential differently.
Anyway it's an interesting choice to think about and discuss, thanks Andrew.
P.S. I added a link to your tournament table here: http://gogameguru.com/links/ - Korea almost looks resurgent right now, but with so little data it's too random to say.
Posts: 6727 Location: Cambridge, UK Liked others: 436 Was liked: 3720
Rank: UK 4 dan
KGS: Uberdude 4d
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Yeah, in that case the big black group doesn't actually have two eyes yet so although it's pretty huge and unlikely to get into trouble, you never know what could happen in the fighting and that half eye could come in handy. I mentioned that throw-in because the issue arose in a recent tournament game of mine where the group did have two clear eyes so the throw-in was a definite mistake in that case, see move 66:
I've just realised another potential downside of the throw-in, but one that's pretty unlikely to ever come up: it does actually give more liberties to the outside black stones which become solidly connected so there could be some situation in which a ladder or other form of damezumari crashing into them is affected.
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nickxyzt
here and has a really good result.
seems best to me.
pretty well forces 
, now or in the next few moves.
is gote, it leaves behind 
, a nice yose.
directly?
]
, but...