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Corner from game
http://lifein19x19.com/viewtopic.php?f=15&t=12140
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Author:  emeraldemon [ Fri Aug 07, 2015 9:26 am ]
Post subject:  Corner from game

What should white have done here?

Click Here To Show Diagram Code
[go]$$Bcm1 White to play
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | . . O X X O . . O . . . . . . . O O O |
$$ | . . O X X O . . . , . . . O . O . . . |
$$ | . . O O X X X . O . . O . . . . . . . |
$$ | . . . . O O X . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


In the game white lost the corner and resigned:

Click Here To Show Diagram Code
[go]$$B Moves 155 to 164
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | . 3 O X X O . . O . . . . . . . O O O |
$$ | . 4 O X X O . . . , . . . O . O . . . |
$$ | . 0 O O X X X . O . . O . . . . . . . |
$$ | 8 5 . 2 O O X . . . . . . . . . . . . |
$$ | . 9 6 . 7 1 . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White 4 @ 5 easily lives, but I'm sure white wanted the most points possible.

Click Here To Show Diagram Code
[go]$$Bcm1 Alive
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | . 3 O X X O . . O . . . . . . . O O O |
$$ | . . O X X O . . . , . . . O . O . . . |
$$ | . . O O X X X . O . . O . . . . . . . |
$$ | . 4 . 2 O O X . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


It looks like playing the hane instead of solid connect might work, but maybe there's an attack I'm missing:

Click Here To Show Diagram Code
[go]$$Bcm1 White to play
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | . 3 O X X O . . O . . . . . . . O O O |
$$ | . 4 O X X O . . . , . . . O . O . . . |
$$ | . . O O X X X . O . . O . . . . . . . |
$$ | . 5 6 . O O X . . . . . . . . . . . . |
$$ | . 8 . 2 . 1 7 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This way black captures 2 stones, so maybe it's actually worse?

Author:  Loons [ Sat Aug 08, 2015 1:55 pm ]
Post subject:  Re: Corner from game

Can you quickly show why :w8: cannot be D1 in your last diagram?

Author:  DrStraw [ Sat Aug 08, 2015 2:13 pm ]
Post subject:  Re: Corner from game

Loons wrote:
Can you quickly show why :w8: cannot be D1 in your last diagram?


Mainly because D1 is occupied. If you meant E1 then :

Click Here To Show Diagram Code
[go]$$Bcm1 White to play
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | 7 X O X X O . . O . . . . . . . O O O |
$$ | 6 O O X X O . . . , . . . O . O . . . |
$$ | 5 . O O X X X . O . . O . . . . . . . |
$$ | . X O . O O X . . . . . . . . . . . . |
$$ | . 3 4 O 2 X 1 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  Loons [ Sat Aug 08, 2015 2:18 pm ]
Post subject:  Re: Corner from game

Oh, yes, that potential ko is a picnic for black.

Edit: However, white took sente against living with points in DrStraw's diagram. Versus... Living in gote with ~3 points in emeraldemon's second diagram.

Emeraldemon's last diagram is slightly harder for me to count. White has... Five points in gote?

Edit edit : Which is to say, DrStraw's position ends leaving a 4 point gote after white's implicit last move. Eight. I should really count in a consistent and comparable way. Is it actually worth 2 points for white?

Author:  emeraldemon [ Sat Aug 08, 2015 3:07 pm ]
Post subject:  Re: Corner from game

Now I'm more confused. Isn't the line in DrStraw's diagram seki? Is there a ko I'm missing?

Author:  DrStraw [ Sat Aug 08, 2015 3:43 pm ]
Post subject:  Re: Corner from game

emeraldemon wrote:
Now I'm more confused. Isn't the line in DrStraw's diagram seki? Is there a ko I'm missing?


Yes, it is seki.

Author:  Loons [ Sat Aug 08, 2015 7:05 pm ]
Post subject:  Re: Corner from game

Click Here To Show Diagram Code
[go]$$Bcm1 White to play
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | X X O X X O . . O . . . . . . . O O O |
$$ | O O O X X O . . . , . . . O . O . . . |
$$ | X . O O X X X . O . . O . . . . . . . |
$$ | . X O . O O X . . . . . . . . . . . . |
$$ | . X O O O X X . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Did I turn into a DDK? Bottom left is unsettled.

Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | X X O X X O . . O . . . . . . . O O O |
$$ | O O O X X O . . . , . . . O . O . . . |
$$ | X . O O X X X . O . . O . . . . . . . |
$$ | 1 X O . O O X . . . . . . . . . . . . |
$$ | . X O O O X X . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White has lived in gote, and there are eight points in gote at stake.

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | 7 . X . X O . O O . . . . . X . X X O |
$$ | 6 X O X X O . . O . . . . . . . O O O |
$$ | . O O X X O . . . , . . . O . O . . . |
$$ | 5 . O O X X X . O . . O . . . . . . . |
$$ | . X O . O O X . . . . . . . . . . . . |
$$ | . 3 4 O 2 X 1 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Picnic (ish) ko for black. White would have needed an unremoveable ko threat.

Author:  DrStraw [ Sat Aug 08, 2015 7:11 pm ]
Post subject:  Re: Corner from game

I assumed that W would play as in your second diagram and B would capture, giving seki. In the third diagram B just connects with 7 and it reverts.

Author:  Loons [ Sat Aug 08, 2015 7:17 pm ]
Post subject:  Re: Corner from game

Oh, yes, sorry, the implicit :w8: and :b9: made it slightly unclear to me, also because :b9: was gote it shouldn't be implicitly played? What does 7... connect revert to? Wait, I will make some coffee, and hopefully begin reading sensibly.

Author:  Loons [ Sat Aug 08, 2015 7:27 pm ]
Post subject:  Re: Corner from game

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | 9 7 X . X O . O O . . . . . X . X X O |
$$ | 6 X O X X O . . O . . . . . . . O O O |
$$ | . O O X X O . . . , . . . O . O . . . |
$$ | 5 8 O O X X X . O . . O . . . . . . . |
$$ | 0 X O . O O X . . . . . . . . . . . . |
$$ | . 3 4 O 2 X 1 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White has lived in gote with ... what, 6 points? But black would not play this way.

Using some consistent kind of counting, Emeraldemon's last diagram was worth 2 1/2 points, and the solid connect turned out to be worth 2 points, where solidly connecting was worth 1 1/2 (just over) points. Possibly I need to go back and read DrStraw on this because I feel like I am that crazy person rambling.

Author:  DrStraw [ Sat Aug 08, 2015 8:07 pm ]
Post subject:  Re: Corner from game

Loons wrote:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | 9 7 X . X O . O O . . . . . X . X X O |
$$ | 6 X O X X O . . O . . . . . . . O O O |
$$ | . O O X X O . . . , . . . O . O . . . |
$$ | 5 8 O O X X X . O . . O . . . . . . . |
$$ | 0 X O . O O X . . . . . . . . . . . . |
$$ | . 3 4 O 2 X 1 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White has lived in gote with ... what, 6 points? But black would not play this way.

Using some consistent kind of counting, Emeraldemon's last diagram was worth 2 1/2 points, and the solid connect turned out to be worth 2 points, where solidly connecting was worth 1 1/2 (just over) points. Possibly I need to go back and read DrStraw on this because I feel like I am that crazy person rambling.


You are right. I answered quickly and did not think about :w8:

Author:  emeraldemon [ Sun Aug 09, 2015 1:08 pm ]
Post subject:  Re: Corner from game

Thanks for looking at this. It sounds like since the seki doesn't work, protecting with the hane makes the white group live with points?

Click Here To Show Diagram Code
[go]$$Bcm1 White saves the corner
$$ ---------------------------------------
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X . X O . . O X . . . . . . . O O . |
$$ | . . . X O . . O X . . X . . O . O . O |
$$ | . . . , . O . O X , . . X X O O X O . |
$$ | . . X . . . O X . . O X . . O X X X . |
$$ | . . X O O O X X . . X O O X O O O X . |
$$ | . X . . . X . . . X . X O O O . O X . |
$$ | . . O O O X . . . . X X X X . O X O . |
$$ | . . O X X . . . . X O O O . O . X . . |
$$ | . O X X . . X . . , X . O . O X X . . |
$$ | . O O X . X O X X . X O . . X . . . . |
$$ | . O X . . O . O O X X O . . . . . X . |
$$ | . X . X . . O . . O O X X . . . . . X |
$$ | . . X . X O . O O . . . . . X . X X O |
$$ | . 3 O X X O . . O . . . . . . . O O O |
$$ | . 4 O X X O . . . , . . . O . O . . . |
$$ | . . O O X X X . O . . O . . . . . . . |
$$ | . . . . O O X . . . . . . . . . . . . |
$$ | . . . 2 . 1 7 . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I thought this was a relatively straightforward position, but it seems complicated to me now.

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