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Why can't you just do this?
http://www.lifein19x19.com/viewtopic.php?f=11&t=12807
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Author:  asdf [ Thu Mar 10, 2016 7:50 pm ]
Post subject:  Why can't you just do this?

Why can't black just go where I put the black circle and take out the whites with the red X's?

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Author:  EdLee [ Thu Mar 10, 2016 8:15 pm ]
Post subject: 

The three :wx: stones still have 2 liberties -- at (x) and (y):
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 1 O . . . . . .
$$ | x P X . . . . . .
$$ | y P P X . . . . .
$$ | . X X O O . . . .
$$ | . X O X . O . . .
$$ | . . . X . . . . .
$$ | . . . . . . . . .[/go]

In addition, W can capture the :bc: stone with :w2: ...
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 1 O . . . . . .
$$ | . P B 2 . . . . .
$$ | . P P X . . . . .
$$ | . X X O O . . . .
$$ | . X O X . O . . .
$$ | . . . X . . . . .
$$ | . . . . . . . . .[/go]
...Resulting in this situation:
Click Here To Show Diagram Code
[go]$$B Captured: :bc:
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . 1 O . . . . . .
$$ | . O . 2 . . . . .
$$ | . O O X . . . . .
$$ | . X X O O . . . .
$$ | . X O X . O . . .
$$ | . . . X . . . . .
$$ | . . . . . . . . .[/go]

The situation is completely different if everything is shifted one line toward the edge --
Here, the 3 :wx: stones have only 1 liberty left, at (z):
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | z O . . . . . . .
$$ | P X . . . . . . .
$$ | P P X . . . . . .
$$ | X X O O . . . . .
$$ | X O X . O . . . .
$$ | . . X . . . . . .
$$ | . . . . . . . . .[/go]
This time, :b1: removes the last liberty (z);
Black captures and removes the 3 :wx: stones...
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | 1 O . . . . . . .
$$ | P X . . . . . . .
$$ | P P X . . . . . .
$$ | X X O O . . . . .
$$ | X O X . O . . . .
$$ | . . X . . . . . .
$$ | . . . . . . . . .[/go]
...Resulting in this situation:
Click Here To Show Diagram Code
[go]$$B Captured: :wx: :wx: :wx:
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | 1 O . . . . . . .
$$ | . X . . . . . . .
$$ | . . X . . . . . .
$$ | X X O O . . . . .
$$ | X O X . O . . . .
$$ | . . X . . . . . .
$$ | . . . . . . . . .[/go]

Make sure you clearly see and count every liberty. :)

Author:  RobertJasiek [ Thu Mar 10, 2016 11:12 pm ]
Post subject:  Re: Why can't you just do this?

The edge of the board is part of the grid and so provides liberties.

Author:  longshanks [ Fri Mar 11, 2016 2:18 am ]
Post subject:  Re: Why can't you just do this?

Others have already answered this, but more simply I think as a beginner you forget that the first line of the grid on which you can make legal moves is actually the edge of the grid.

Author:  EdLee [ Fri Mar 11, 2016 4:00 am ]
Post subject: 

Hi longshanks, good guess. :) And possibly have to do with chess.

Author:  DrStraw [ Fri Mar 11, 2016 6:05 am ]
Post subject:  Re: Why can't you just do this?

asdf is the name of a troll who frequently is seen on KGS in the ECR. I suspect this is not a genuine question.

Author:  asdf [ Fri Mar 11, 2016 7:21 am ]
Post subject:  Re: Why can't you just do this?

Thanks ed & others. I didn't realise you could play on the edge! It was killing me tryin to watch AlphaGo vs Lee Sedol. Another thing I found interesting was the programming decision to have Alpha go for the higher probability of winning over getting more points, i.e. if a move will give 90% chance of winning by 2 points, it will be preferred over an %80 chance of winning by 12 points. I get they really want to prove themselves by winning, but i think from an evaluation standpoint, it's better to find a more even balance towards obtaining points. You could evaluate much better how good alpha is by having games where he wins by alot, rather than winning by a little everytime.

Author:  hyperpape [ Fri Mar 11, 2016 8:28 am ]
Post subject:  Re: Why can't you just do this?

DrStraw wrote:
asdf is the name of a troll who frequently is seen on KGS in the ECR. I suspect this is not a genuine question.
asdf isn't a particularly unique username, unlike DrStraw or hyperpape, where you assume it's the same person across multiple forums. One of my high school friends was "asdfinator" on some service 15 years ago because "asdf" was taken (and neither of them were the KGS troll, as far as I can tell).

In this case, I think it would be better to not accuse someone of being a troll until there's more reason.

Author:  Nyanjilla [ Fri Mar 11, 2016 8:44 am ]
Post subject:  Re: Why can't you just do this?

DrStraw wrote:
asdf is the name of a troll who frequently is seen on KGS in the ECR. I suspect this is not a genuine question.


This person has far better English than the user of that name on KGS. It is a fairly common mash-the-keyboard type of name from a qwerty board.

One thing I find difficult when teaching beginners is looking at a position as a beginner does. To me it seems so obvious that that black move couldn't possibly work, but I've met similar questions before.

Author:  Uberdude [ Fri Mar 11, 2016 9:13 am ]
Post subject:  Re: Why can't you just do this?

asdf: Also something to think about is if black could have captured those 3 stones like you thought with the edge not being liberties, white could also have captured three black stones further down (same column, row 18 in your picture) for sometime before. Looking at a position from the point of view of both players is important to avoid blind spots.

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