Five Stones On The Third Line In The Corner / Discussion

[Diagram]
PRE WME Five stones on the third line in the corner  

Go Proverbs Illustrated says that this shape is alive. Since I don't have the book, I'm not sure whether that means living with points or living in seki. What's the status of this group if Black plays first?

--MrTenuki

Go proverbs illustrated gives this explanation of how this group is alive. (I only have this from ([ext] hearsay)




fractic: I'm not a dan player but I've taken a look at this position. I think Black can get a ko or a seki. I would like a stronger player to take a look at this because some variations get rather complicated.

[Diagram]
the vital point?  

fractic: B1 looks like a vital point in this shape. White can try a lot of moves.

[Diagram]
White a  

fractic: White a leads to a ko because white is short on liberties.

[Diagram]
White b  

fractic: This also leads to a ko. The order of W4 and W6 can be interchanged.

[Diagram]
White c  

fractic: White can get a seki in gote like this.

[Diagram]
White d  

fractic: This leads to the same result as the previous variation.

[Diagram]
White d  

fractic: I think W4 and W6 are the strongest resistance. Black can't play B7 at a because then white pushes out once more before playing b. So White can play a and play a ko. The ko is quite risky for Black too.

[Diagram]
 

Anonymous: What happens if W plays directly at 'b' instead of setting up the ko? I spent a while with variations but can't find a way for B to kill.

[Diagram]
B11 at a  

fractic: Black descends with B7. W8 to Black a is one way to reach a ko or seki for white. I thought the previous diagram was stronger resistance because blocking with B7 is a bit unnatural but if White is allowed to push twice all the variations involving this descent don't work because white gets an extra liberty.

Note that if White makes seki now the count is 2 points better for Black than it would have been if Black had played hane tsugi at W8 and W2.

[Diagram]
 

Anonymous: Yes, I considered the descent for B. But I couldn't find a refutation for W8. A couple of variations follow.

fractic: I think you are right. I just completely missed W8 when I first analyzed this. Perhaps B5 is wrong..

[Diagram]
a and b miai  
[Diagram]
a and b miai  
[Diagram]
5 at the marked stone  
[Diagram]
5 at the marked stone  

[Diagram]
 

Anonymous: Another good idea for B5, this seems to lead to ko:

[Diagram]
Ko, W gets first capture and B must win twice in order to attack from the outside.  

Anonymous: The best defense I could find for W.

[Diagram]
W gets first capture, B can win by filling at 6, so a direct ko?  
[Diagram]
This attempt at seki fails -- 8@2, leaves the marked stone and 'a' miai for the kill  
[Diagram]
This attempt at seki leads to ko. 10@2, 11 at the marked stone, B can capture the ko first.  

[Diagram]
Five stones on the third line in the corner  

Andy Pierce: I think this is a stronger attack for black. There are lots of variations, but black can get a ko. It's often better to do the straight connected descent than to try the hane and owe a patch up move at the descent spot later.

xela: Can you show some variations? All I can see is seki.

[Diagram]
variation 1: seki  
[Diagram]
variation 2: W10 can tenuki for seki  
[Diagram]
variation 3: white lives with territory  


xela: Did I miss anything here?

[Diagram]
Five stones on the third line in the corner  

fractic: I don't think B1 works. White should take the vital point right away.

[Diagram]
 

kevinwm: What about this variation? Is there any chance for a double-ko here?

kevinwm: Also, let's start a discussion of Four stones on the third line in the corner. Clearly black can kill with first move. Can white live unconditionally with first move?



tapir: I am not sure we should present the main page as research results, when it is missing some variations even I see and a clear answer what happens after the placement by Black and a White hane as answer. I would rather make a tsumego collection out of it than a statement of research results (it sounds too proud for what happened on L19 and the page).


Compare Segoe result and new result...

[Diagram]
Segoe (+ endgame is gote for both)  
[Diagram]
Recent Research (B9 threatens to kill = Black's sente)  

tapir: Here, Black is 4 points better than in the Segoe line, but...

[Diagram]
Hane (1 sequence)  

In this variation White ends with only 4 points, with Black having 3 points territory less + 1 prisoner more. That is White is 1 point better off than in the Segoe solution.

[Diagram]
Seki + (simplified) endgame  

Here, in another sequence after the hane, White lost all 5 points of territory, but destroyed the same amount of Black's territory. If Black can't risk a ko, and has to play B2 at B4 the final result is the same.

If the outside isn't clearly Black's territory, the count is different, but obviously depends on the exact configuration... however, as the aji after the hane / hanging connection will then be more valuable, White should be even better off.


Missing variations

[Diagram]
Seki  

tapir: I would prefer this Seki over a living inside (Segoe variation) in many cases, because of the aji of a. White can either connect or play two moves on the outside.

[Diagram]
a and b miai for escape or seki  
[Diagram]
ko  

bacteria: In my reading, W4 results in ko.

tapir: What is with W6 at B7?

[Diagram]
dead?  

Five Stones On The Third Line In The Corner / Discussion last edited by Dieter on January 15, 2013 - 14:30
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