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Which color would you take?
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Author:  HermanHiddema [ Tue Oct 02, 2012 6:23 am ]
Post subject:  Which color would you take?
So, here's an interesting question I ran into some time ago.

Suppose you are given the following board position:

Click Here To Show Diagram Code
[go]$$B
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . , . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


Black has been given quite a handicap.

In return, black must pass every second move, effectively giving white two moves in a row every turn.

You are given the choice of color. Would you take black, with all those handicap stones, or white, who gets two moves in a row?
Author:  p2501 [ Tue Oct 02, 2012 6:31 am ]
Post subject:  Re: Which color would you take?
So does white get to play two moves initially or would it be white black white white...?
Author:  jts [ Tue Oct 02, 2012 6:35 am ]
Post subject:  Re: Which color would you take?
I'd take black... it's impossible for W to make eyes on the edge, right?
Author:  HermanHiddema [ Tue Oct 02, 2012 6:41 am ]
Post subject:  Re: Which color would you take?
p2501 wrote:
So does white get to play two moves initially or would it be white black white white...?


Oh, sorry, black starts! So B-W-W-B-W-W etc
Author:  Mef [ Tue Oct 02, 2012 6:42 am ]
Post subject:  Re: Which color would you take?
HermanHiddema wrote:
So, here's an interesting question I ran into some time ago.

Suppose you are given the following board position:

Click Here To Show Diagram Code
[go]$$B
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . , . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


Black has been given quite a handicap.

In return, black must pass every second move, effectively giving white two moves in a row every turn.

You are given the choice of color. Would you take black, with all those handicap stones, or white, who gets two moves in a row?


This is a fun exercise -

I think would want white...after a quick look at things, I think black can never touch the edge of the board, because any play on the 2nd line white blocks and extends. Any play on the first line, white can atari and capture next turn. From this alone, I would estimate W can get half the points on the edge, making it about 21 to 25. The question really becomes, can black live in the center?

Click Here To Show Diagram Code
[go]$$B W12 Marked.
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . 9 . X . . |
$$ | . . X . . 6 5 0 X . . |
$$ | . . X . 8 , 2 W X . . |
$$ | . . X . . 4 1 . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


This doesn't look promising...maybe there's a better way...


Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


After this W can connect at A and B, black can never cut W's shape...of course, even if you make a capturing race here, B needs twice the liberties, so if we say W has 7 libs inside, W gets 14 moves outside...hmm...this might end up being close...I think I still want white though though
Author:  Eizero [ Tue Oct 02, 2012 9:06 am ]
Post subject:  Re: Which color would you take?
Black obviously... White can't possibly win unless black is much weaker.

With 3 stones every time for white it should still favor black.

With 4 stones every time for white I'm uncertain.

edit: With 3 stones it looks like white can't live in center if black plays first in the center. With 4 stones it should defiantly favour white.
Author:  Tryss [ Tue Oct 02, 2012 10:56 am ]
Post subject:  Re: Which color would you take?
jts wrote:
I'd take black... it's impossible for W to make eyes on the edge, right?


I think white can easily live on the corner :
Click Here To Show Diagram Code
[go]$$B
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . 2 . . |
$$ | . . X X X X X X X 4 . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . , . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


But, yes, I'd take black too :mrgreen:
Author:  jts [ Tue Oct 02, 2012 11:17 am ]
Post subject:  Re: Which color would you take?
I was thinking of the sides, but I guess W can get eyes there as well:

Click Here To Show Diagram Code
[go]$$B
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . , . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . 5 2 4 6 8 9 . . |
$$ | . . . W 0 . . . . . . |
$$ +-----------------------+[/go]


Maybe I was rash... fools rush in, as they say.
Author:  HermanHiddema [ Tue Oct 02, 2012 11:39 am ]
Post subject:  Re: Which color would you take?
Some food for thought:

Any stone Black places on the board that is not directly connected to his existing stones, can be captured by white.
Author:  HermanHiddema [ Tue Oct 02, 2012 11:47 am ]
Post subject:  Re: Which color would you take?
Mef wrote:
This is a fun exercise -

I think would want white...after a quick look at things, I think black can never touch the edge of the board, because any play on the 2nd line white blocks and extends. Any play on the first line, white can atari and capture next turn. From this alone, I would estimate W can get half the points on the edge, making it about 21 to 25. The question really becomes, can black live in the center?

Click Here To Show Diagram Code
[go]$$B W12 Marked.
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . 9 . X . . |
$$ | . . X . . 6 5 0 X . . |
$$ | . . X . 8 , 2 W X . . |
$$ | . . X . . 4 1 . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


This doesn't look promising...maybe there's a better way...


Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


After this W can connect at A and B, black can never cut W's shape...of course, even if you make a capturing race here, B needs twice the liberties, so if we say W has 7 libs inside, W gets 14 moves outside...hmm...this might end up being close...I think I still want white though though


In this diagram:

Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


Why not :w10: at :bc:?
Author:  shapenaji [ Tue Oct 02, 2012 12:13 pm ]
Post subject:  Re: Which color would you take?
HermanHiddema wrote:
Mef wrote:
This is a fun exercise -

I think would want white...after a quick look at things, I think black can never touch the edge of the board, because any play on the 2nd line white blocks and extends. Any play on the first line, white can atari and capture next turn. From this alone, I would estimate W can get half the points on the edge, making it about 21 to 25. The question really becomes, can black live in the center?

Click Here To Show Diagram Code
[go]$$B W12 Marked.
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . . . 9 . X . . |
$$ | . . X . . 6 5 0 X . . |
$$ | . . X . 8 , 2 W X . . |
$$ | . . X . . 4 1 . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


This doesn't look promising...maybe there's a better way...


Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


After this W can connect at A and B, black can never cut W's shape...of course, even if you make a capturing race here, B needs twice the liberties, so if we say W has 7 libs inside, W gets 14 moves outside...hmm...this might end up being close...I think I still want white though though


In this diagram:

Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


Why not :w10: at :bc:?


EDIT: Hah, nevermind, yeah white lives...
Author:  Mef [ Tue Oct 02, 2012 12:19 pm ]
Post subject:  Re: Which color would you take?
HermanHiddema wrote:
In this diagram:

Click Here To Show Diagram Code
[go]$$B W12 Marked. B13 Marked
$$ +-----------------------+
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ | . . X X X X X X X . . |
$$ | . . X . B 6 a . X . . |
$$ | . . X W 9 5 8 . X . . |
$$ | . . X b 0 1 2 . X . . |
$$ | . . X . . 4 . . X . . |
$$ | . . X . . . . . X . . |
$$ | . . X X X X X X X . . |
$$ | . . . . . . . . . . . |
$$ | . . . . . . . . . . . |
$$ +-----------------------+[/go]


Why not :w10: at :bc:?


Simple - because I was trying to quickly read it out off of a text diagram (= Yes your :w10: is better, and in fact at this point I'm not entirely convinced that B can live in this game. I have a nagging suspicion he might be able to making a capturing race in the middle right away, but I haven't put a lot of thought into what exact killing shapes white may be able to make.
Author:  mithra [ Mon Oct 15, 2012 7:59 am ]
Post subject:  Re: Which color would you take?
I get W+6 (only a try).
W gets the edge as a connected chain and many points.
B must hurry to make life in the center, W sacrifices a dozen stones there for semedori as dango.
Author:  mithra [ Tue Oct 16, 2012 7:07 am ]
Post subject:  Re: Which color would you take?
oh, I see now that W can capture even a stone on a 5-5 point, so maybe the semedori strategy is not at all necessary and W can live in the center...
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