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Offline Gérard TAILLE
 Post subject: Re: Quite strange result in area counting rules
Post #21 Posted: Sat Jul 31, 2021 2:04 pm 
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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?
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Offline Gérard TAILLE
 Post subject: Re: Quite strange result in area counting rules
Post #22 Posted: Sun Aug 01, 2021 2:29 am 
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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?

This post by Gérard TAILLE was liked by: dhu163
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Offline luigi
 Post subject: Re: Quite strange result in area counting rules
Post #23 Posted: Sun Aug 01, 2021 5:44 am 
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Am I missing something? Or do these examples really make no sense?
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Offline Pio2001
 Post subject: Re: Quite strange result in area counting rules
Post #24 Posted: Sun Aug 01, 2021 6:41 am 
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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.
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Offline Gérard TAILLE
 Post subject: Re: Quite strange result in area counting rules
Post #25 Posted: Sun Aug 01, 2021 8:46 am 
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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?
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Offline Pio2001
 Post subject: Re: Quite strange result in area counting rules
Post #26 Posted: Sun Aug 01, 2021 12:35 pm 
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I understand now: if Black plays elsewhere, White can take back the first ko.
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Offline Gérard TAILLE
 Post subject: Re: Quite strange result in area counting rules
Post #27 Posted: Sun Aug 01, 2021 12:44 pm 
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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.
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Offline Gérard TAILLE
 Post subject: Re: Quite strange result in area counting rules
Post #28 Posted: Sun Aug 01, 2021 12:47 pm 
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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 ?
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Offline luigi
 Post subject: Re: Quite strange result in area counting rules
Post #29 Posted: Tue Aug 03, 2021 6:10 am 
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I get it now, thanks. This should bury NSSK for good. :)
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