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Quite strange result in area counting rules
http://lifein19x19.com/viewtopic.php?f=45&t=18292
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Author:  Gérard TAILLE [ Sat Jul 31, 2021 2:04 pm ]
Post subject:  Re: Quite strange result in area counting rules

Another example of anomalie with NSSK:

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


Click Here To Show Diagram Code
[go]$$W White to play
$$ ---------------------------------------
$$ | . O X X . X O . . . . . . . . . . . . |
$$ | O 2 O X X X O . . . . . . . . . . . . |
$$ | . O X X O O O . . . . . . . . X . . . |
$$ | O O O X X X O . . , . . . . . , . . . |
$$ | O X X X O O O . . . . . . . . . . . . |
$$ | . O O 1 X X . . . . . . . . . . . . . |
$$ | . O X X X . . . . . . . . . . . . . . |
$$ | O . X . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . X . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


After the exchange :w1: :b2: in the diagram above, comes the most stupid move you can imagine : white pass !!
Now if black takes the second ko by playing A19 then white is able to retake the ko immediatly.
Because black loses if she passes also, black has no solution.

Isn't it an anomalie?

Author:  Gérard TAILLE [ Sun Aug 01, 2021 2:29 am ]
Post subject:  Re: Quite strange result in area counting rules

A little change to have a position more fun:

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

:b1: ?? is a terrible mistake isn't it?

Author:  luigi [ Sun Aug 01, 2021 5:44 am ]
Post subject:  Re: Quite strange result in area counting rules

Am I missing something? Or do these examples really make no sense?

Author:  Pio2001 [ Sun Aug 01, 2021 6:41 am ]
Post subject:  Re: Quite strange result in area counting rules

Gérard TAILLE wrote:
Another example of anomalie with NSSK:


The problem with these examples is that the player who wants take advantage of NSK must pass forever in order to be able to retake the ko, thus give away the rest of the board to his opponent.
Therefore no one can gain anything with NSK when there is something else left on the board.

That's why in the example that I gave, Black's groups are so heavy. If there was an eyespace containing more than 3 intersections in Black's territory, White could win by stealing it while Black passes.
As soon as Black plays a stone on the board other than retaking the ko, the superko behaviour is back to normal.

Author:  Gérard TAILLE [ Sun Aug 01, 2021 8:46 am ]
Post subject:  Re: Quite strange result in area counting rules

Pio2001 wrote:
Gérard TAILLE wrote:
Another example of anomalie with NSSK:


The problem with these examples is that the player who wants take advantage of NSK must pass forever in order to be able to retake the ko, thus give away the rest of the board to his opponent.
Therefore no one can gain anything with NSK when there is something else left on the board.

That's why in the example that I gave, Black's groups are so heavy. If there was an eyespace containing more than 3 intersections in Black's territory, White could win by stealing it while Black passes.
As soon as Black plays a stone on the board other than retaking the ko, the superko behaviour is back to normal.


What do you mean Pio2001?

Click Here To Show Diagram Code
[go]$$B Black to play
$$ ---------------------------------------
$$ | 5 O X X . X O . . . . . . . . . . . . |
$$ | O 3 O X X X O . . . . . . . . . . . . |
$$ | O O X X O O O . . . . . . . . X . . . |
$$ | . O O X X X O . . , . . . . . , . . . |
$$ | O 1 X X O O O . . . . . . . . . . . . |
$$ | . O O 2 X X . . . . . . . . . . . . . |
$$ | O O X X X . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | O X . X . . . . . . . . . . . . . . . |
$$ | . X . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:w4: pass

Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | X 6 X X . X O . . . . . . . . . . . . |
$$ | O X . X X X O . . . . . . . . . . . . |
$$ | O O X X O O O . . . . . . . . X . . . |
$$ | . O O X X X O . . , . . . . . , . . . |
$$ | O X X X O O O . . . . . . . . . . . . |
$$ | . O O O X X . . . . . . . . . . . . . |
$$ | O O X X X . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | O X . X . . . . . . . . . . . . . . . |
$$ | . X . , . . . . . , . . . . . , . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

and black stones will be captured won't they?

Author:  Pio2001 [ Sun Aug 01, 2021 12:35 pm ]
Post subject:  Re: Quite strange result in area counting rules

I understand now: if Black plays elsewhere, White can take back the first ko.

Author:  Gérard TAILLE [ Sun Aug 01, 2021 12:44 pm ]
Post subject:  Re: Quite strange result in area counting rules

Pio2001 wrote:
I understand now: if Black plays elsewhere, White can take back the first ko.

Yes that is the point. And if black passes after :w6: then white passes also and wins the game.

Author:  Gérard TAILLE [ Sun Aug 01, 2021 12:47 pm ]
Post subject:  Re: Quite strange result in area counting rules

luigi wrote:
Am I missing something? Or do these examples really make no sense?

Luigi, is it clearer with the sequence I showed in https://lifein19x19.com/viewtopic.php?p=266277#p266277 ?

Author:  luigi [ Tue Aug 03, 2021 6:10 am ]
Post subject:  Re: Quite strange result in area counting rules

I get it now, thanks. This should bury NSSK for good. :)

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