Five stones on the third line in the corner

   
[Diagram]

Five stones on the third line in the corner

This is the Five stones on the Third line in the Corner and according to Segoe Kensaku's Go Proverbs Illustrated it is alive as it stands.

If it was not in the corner but on the side it would be the Five stones on the third line its status would depend on who moves first


More recent investigations is somewhat disputing Segoe's conclusion. But has not reached a final conclusion yet.

Everything here is therefore to be taken as research in progress not as final conclusions.

We start with an short overview of the most easy variations. under Old page pre WME more variations are found


Table of contents Table of diagrams
Five stones on the third line in the corner
Segoe's conclusion
the vital point?
White ''c''
The descend
White defends

PRE WME Five stones on the third line in the corner
[Go Proverbs Illustrated]
the vital point?
White ''a''
White ''b''
White ''c''
White ''d''
White ''d''

B11 at ''a''

a and b miai
a and b miai
5 at the marked stone
5 at the marked stone

Ko, W gets first capture and B must win twice in order to attack from the outside.
W gets first capture, B can win by filling at 6, so a direct ko?
This attempt at seki fails -- 8@2, leaves the marked stone and 'a' miai for the kill
This attempt at seki leads to ko. 10@2, 11 at the marked stone, B can capture the ko first.

Five stones on the third line in the corner
variation 1: seki
variation 2: W10 can tenuki for seki
variation 3: white lives with territory
Five stones on the third line in the corner

Segoe's conclusion

[Diagram]

Segoe's conclusion

Segoe's Go proverbs illustrated gives only this diagram to show that this group is alive.

After W4 the group is undeniably alive. But questions are raised about the first move in this sequence

(See also [ext] http://www.lifein19x19.com/forum/viewtopic.php?p=30778#p30778)

Depending on who plays next in this corner White lives with 4 to 5 points of territory


New research for move 1

The recent investigations attack with another B1

Directly to the 1-2 point

[Diagram]

the vital point?

B1 is at a vital point in this shape. White can try a lot of moves.

The most simple continuation that results in a living group is white c a move that leads to a seki in gote

for the variations following after a, b and d look at the old page below

[Diagram]

White c

White c results in a seki in gote.

We do not know if Segoe had this in mind. White is alive, but has lost his territory.

and to be honest it is a bit disapointed for White and so this is better for Black than Segoe's conclusion.


The Descend (bad for Black)

[Diagram]

The descend

An other B1 is the decend but if white takes the vital point with W2 he is alive.


White defends

[Diagram]

White defends

Although it is still uncertain if White needs to defend this shape W1 followed by W3 are one way to do so. (there are other options) Notice that if black plays continues with B4 and B6 White needs to defend on W7 or any of the points a because after B6 it is a rectangular eight in the corner


See also


[Diagram]

Please do not remove this diagram it is to create a empty line in the list of diagrams


Old page Pre WME

Below is the page from before the last main edit, it contains many more variations that are not jet integrated in the article above.


This page needs wiki master editing.
Comment: I (MrTenuki) wrote this page back in 2006 as an SDK in order to fix the dead link from Go Proverbs Illustrated. Dan-level analysis would be helpful as this page is currently linked from the soon-to-be-featured article "corner shapes."


[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]

Anonymous: What happens if W defends this way?


[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.


This is a copy of the living page "Five stones on the third line in the corner" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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