RobertJasiek wrote:
I repeat my question for the particular position at the current moment.
Before that, let me digress a little again. That will make it unnecessary to fight your way through
GT territory rules:: Honte's loops and cycles.
Let...
be ko captures / re-captures into ko-shape #1;
be ko captures / re-captures into ko-shape #2; and so on...
be GENUINE "pass".
be "pass-for-ko" of the "traditional" J89's kind; i.e. ONE "pass" for lifting the ko-ban of ONE particular ko-shape, into which re-capturing is allowed immmediately thereafter.
be "pass-for-all-ko" of your J2003's kind; i.e. ONE "pass" for lifting the ko-bans of EVERY ko-shape, into which re-capturing is allowed immediately thereafter.
be "pass-for-ko" of the "current" J89's kind
(provided my understanding is correct); i.e. ONE "pass" for lifting the ko-ban of ONE particular ko-shape, but into which re-capturing is allowed ONLY after ALL active ko-bans have been lifted before.
etc. genuine moves that do NOT capture/ re-capture into a ko-shape.
WHITE's task in the following formations is to prevent her group(s) from becoming captured. whatsoever the costs.
BLACK's task is the opposite, he has to do everything he can to capture White's group, whatsoever the costs.
+++++++++++++++++++++++++++++++SIMPLE-ko & eye
- Click Here To Show Diagram Code
[go]$$B
$$ +------------------
$$ | X Q . Q . O X . .
$$ | X X Q O O O X . .
$$ | . X X X X X X . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]
Black starts with
.
White dreams of a cycle
..., but also knows that her dream will never become true, as the sequence
(that started with Black's initial move) is forbidden by the rules.
Thus, she can only hope for a cycle
..., which would effectively result in her desired cycle above, but without breaking the rules.
Black, however, likes the sequence
more, with
filling the ko-shape.
Please note that using was sufficient above.
There was NO NEED AT ALL to resort to any of .+++++++++++++++++++++++++++++++DOUBLE-ko
- Click Here To Show Diagram Code
[go]$$B
$$ +----------------
$$ | . Y . Y O X . .
$$ | X X Y O O X . .
$$ | Q X O . O X . .
$$ | . Q O O O X . .
$$ | Q O X X X X . .
$$ | X X X . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .[/go]
Black starts with
.
White already knows very well that the sequence
is forbidden by the rules.
She now dreams of a cycle starting with
, but has to admit that Black would never follow her, as the sequence
is also forbidden by the rules.
A valid alternative for keeping her group alive is
...
Half the length of this cycle (= 3) is an ODD number, which means that -- in principle -- the RIGHT to initiate one of these halves alternates between both players.
Here, Black is FORCED to initiate the second half of the cycle, as
was an atari (as was his initial
as well). However, he might want to refrain from his second
, as White played "only" a
before.
In order to keep the cycle going, both players must cooperate. However, none of these is forced to do so.
The other valid alternative for keeping White's group alive is
..., which effectively results in her desired sequence above, but without breaking the rules.
However, despite half the length of this cycle (= 4) being an EVEN number, cooperation between both players is also necessary to keep this cycle going, as Black will soon realise that
is about the same as
that did not lead to success just before, due to the symmetry of the formation. Being very well aware of this, he might not even want to start with his intial
.
Please note that using was sufficient above.
There was NO NEED AT ALL to resort to any of .Let's now consider what might happen when using the "path-for-ko" options mentioned above.
----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so.
In this case White -- not being aware that the formation is symmetrical -- has the option of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
enables
that would be an atari.
Black is FORCED to play
, in order to make
possible. Otherwise, his group would become captured.
White is able to keep Black busy for a while.
But sooner or later she will realise that her ENFORCED cycle has the same effect as doing nothing. And thus will stop continuing, in order to enable a status confirmation elsewhere on the board.
Please note that half the length of this cycle (= 4) is an EVEN number. This results in the SAME player being able to start every single ENFORCED half of this cycle FOREVER.
This is the very hidden unfortunate side-effect of J89's initial version!----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so.
In this case White -- not being aware that the formation is symmetrical -- has the option of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
enables
that would be an atari.
However,
also enabled
. Therefore, Black is free to continue with playing a GENUINE move, as the danger of his group becoming captured after
has vanished.
Half the length of this cycle (= 3) is an ODD number, which means that the RIGHT to initiate one of these halves alternates between both players.
The transition from the first half of this cycle to the second one is NOT forced. This means that the cycle is an OPTIONAL one.Thus, Black would like the sequence
more, with
being tenuki.
White may be able to continue with
, with
being tenuki again. You you will easily recognise that White -- in principle -- simply continues with a meaningless local sequence, while Black is able to play several moves in a row elsewhere.
----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so.
In this case White -- not being aware that the formation is symmetrical -- has the dream of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
is mandatory for becoming able to play
that would be an atari. However,
is NOT the ONLY precondition that must be fulfilled to really being able to do so!
is mandatory for becoming able to play
, if Black ever wanted to do so (but which is very hazardous to assume).
All former ko bans have been lifted, so White is able to play
, starting another have of White's desired cycle, with both ko-shapes interchanged.
However, is was Black's move
that FINALLY made
a valid move. Black knows for sure that White is hindered to play
without.
Therefore, Black likes the sequence
more, as there is no danger of his group becoming captured.
By capturing once into a DOUBLE-ko, White stops herself from being able to capture into that DOUBLE-ko ever again -- in principle.
There will will be NO cycle, unless Black co-operates. Thus, such cycle will be an OPTIONAL one.+++++++++++++++++++++++++++++++DOUBLE-ko & LARGE eye
- Click Here To Show Diagram Code
[go]$$B
$$ +--------------------------
$$ | . O . O X O . . O O X . .
$$ | O O O X X O X X X O X . .
$$ | X O X . X O O . . O X . .
$$ | . X X X X O O O O O X . .
$$ | X X O O O O X X X X X . .
$$ | O O O X X X X . . . . . .
$$ | X X X X . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .[/go]
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so, and play
into White's LARGE eye at the right, instead.
In this case White -- not being aware that the DOUBLE-ko formation at left is symmetrical -- has the dream of creating the following cycle on her own:
...
Half the length of this cycle (= 3) is an ODD number, which means that the RIGHT to initiate one of these halves alternates between both players.
Here, Black is NOT forced to initiate the second half of the cycle, as White played "only" a
before.
In order to keep the cycle going, both players must cooperate. However, none of these is forced to do so.
Black would like the sequence
etc. more, in order to make sure that White understands that her one-eyed group at right could be taken off the board. Sooner or later, White will admit that continuesly re-capturing into the DOUBLE-ko only delays a result that cannot be prevented anyway.
Please note that using was sufficient above.
There was NO NEED AT ALL to resort to any of .Let's now consider what might happen when using the "path-for-ko" options mentioned above.
----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so, and play
into White's LARGE eye at the right, instead.
Even in this case (please note that
was NO ATARI) White has the option of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
enables
that would be an atari.
Black is FORCED to play
, in order to make
possible. Otherwise, his DOUBLE-ko group would become captured.
White is able to keep Black busy FOREVER!
Sooner or later Black will realise that the ENFORCED cycle that White initiated will make it IMPOSSIBLE to EVER return to White's LARGE eye at the right. He finally admits that White's groups are "uncapturable".
This undesirable result is a direct consequence of the very hidden unfortunate side-effect of J89's initial version!
Please note that Black would have to reduce the liberties of White's group at right to at least TWO BEFORE THE GAME STOPS, if he wanted the status confirmation declaring White's formation to be "dead".----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so, and play
into White's LARGE eye at the right, instead.
In this case White dreams of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
enables
that would be an atari.
However,
also enabled
. Therefore, Black is free to continue with playing a GENUINE move, as the danger of his group becoming captured after
has vanished.
Half the length of this cycle (= 3) is an ODD number, which means that the RIGHT to initiate one of these halves alternates between both players.
The transition from the first half of this cycle to the second one is NOT forced. This means that the cycle is an OPTIONAL one.Thus, Black would like the sequence
more, with
being played into White's eye again.
White may be able to continue with
, with
being played into White's eye again. Sooner or later, White will understand that her one-eyed group at right could be taken off the board, and that continuesly re-capturing into the DOUBLE-ko only delays a result that cannot be prevented anyway.
----------------------------------
#####
#####
Black knows from above that starting with
will not lead to success. Thus, he will refrain from doing so, and play
into White's LARGE eye at the right, instead.
In this case White has the dream of creating the following cycle on her own:
...
is ENFORCED, as
was an atari.
is mandatory for becoming able to play
that would be an atari. However,
is NOT the ONLY precondition that must be fulfilled to really being able to do so!
is mandatory for becoming able to play
, if Black ever wanted to do so (but which is very hazardous to assume).
All former ko bans have been lifted, so White is able to play
, starting another have of White's desired cycle, with both ko-shapes interchanged.
However, is was Black's move
that FINALLY made
a valid move. Black knows for sure that White is hindered to play
without.
Therefore, Black likes the sequence
etc. (with
also played into White's LARGE eye at the right) more, which will easily prove that White's stones at the right can be taken off the board. White has NOT been given any opportunity to lenghten this process!
By capturing once into a DOUBLE-ko, White stops herself from being able to capture into that DOUBLE-ko ever again -- in principle.
There will will be NO cycle, unless Black co-operates. Thus, such cycle will be an OPTIONAL one.+++++++++++++++++++++++++++++++DOUBLE-ko & CHAIN of FALSE eyes
- Click Here To Show Diagram Code
[go]$$B
$$ +--------------------------------
$$ | . O O . O . O X . X O . O X . .
$$ | O X X O O O O X X O O O O X . .
$$ | X X . X X X O X O . O X X X . .
$$ | . . . , X O X X X O O X . . . ,
$$ | . . . . X O X . X O X X . . . .
$$ | . . . . X O X X X O X . . . . .
$$ | . . . . X O O O O X X . . . . .
$$ | . . . . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . . . . .[/go]
Black knows from above that he cannot kill White's group in the DOUBLE-ko directly.
Thus, he starts with
capturing into the ko-shape in the upper left corner.
White knows already that the following TRIPLE-ko cycle will bail her out:
...
(
and
are played in the DOUBLE-ko at right)
Half the length of this cycle (= 3) is an ODD number, which means that the RIGHT to initiate one of these halves alternates between both players.
Here, Black is NOT forced to initiate the second half of the cycle, as
before was NO ATARI.
However, as he is unable to attack White's CHAIN of FALSE eyes from the inside, there is nothing else but a "pass" that he can play.
In this case, the cycle will become
...
Please note that half the length of this cycle (= 6) is an EVEN number. This results in WHITE being able to start every single half of this cycle FOREVER.
This is the ONE AND ONLY application case that makes a SPECIAL REGULATION necessary!!!However, instead of installing a general overall SINGLE-ko ban, the following might have been easier, more user-friendly and less prone to errors:
By the rules of status confirmation, "MOONSHINE LIFE" is declared "dead"!!!Another proposal with the same characteristics :
Capturing into a DOUBLE-ko must never be used as a ko-threat for a SINGLE-ko during status confirmation!!!Let's now consider what might happen when using the "path-for-ko" options mentioned above.
----------------------------------
#####
#####
White's central group that is attached to Black's DOUBLE-ko group has MORE than TWO liberties!
Black knows from above that he will be unable to approach this group, in order to give atari. Thus, he declares defeat outright.
This undesirable result is a direct consequence of the very hidden unfortunate side-effect of J89's initial version!----------------------------------
#####
#####
White knows from above that he will be unable to prevent Black from approaching her central group at the upper edge, which is attached to Black's DOUBLE-ko group, so giving atari. Thus, she declares defeat outright.
----------------------------------
#####
#####
White knows from above that he will be unable to prevent Black from approaching her central group at the upper edge, which is attached to Black's DOUBLE-ko group, so giving atari. Thus, she declares defeat outright.
+++++++++++++++++++++++++++++++Your request
- Click Here To Show Diagram Code
[go]$$B 
pass
$$ +---------------------------------------+
$$ | X X Q . Q . O X Q M O . O X . . . . . |
$$ | . X X Q O O O X Y Q O O O X . . . . . |
$$ | X X . X X X O X T Y O X X X . . . . . |
$$ | . . . , X O X X Y O O X . . . , . . . |
$$ | . . . . X O X . X O X X . . . . . . . |
$$ | . . . . X O X X O X X . . . . . . . . |
$$ | . . . . X O O O O . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
resulted from White capturing into the upper DOUBLE-ko shape with
.
Black has NOT yet played a "pass" for that ko-shape.
resulted from White playing a "pass" for the lower DOUBLE-ko shape.
Before, this point was occupied by
, too, which resulted from Black capturing into that ko-shape with
.
NOT for EACH of the ko to re-capture has been played a "pass" yet. Thus, White must not re-capture into that lower of the DOUBLE-ko shapes, where one of her stones has been captured in a ko long before.
Login
Register
FAQ
Search
jann
because this forces black to pass for 
. 
, 
can flip the double ko one last time, B answers, then 
pass (for left or just normally, doesn't matter, 
captures).
avoids a quick death.
also captures in the double-ko.
recaptures in the corner.
gives atari at Black's double-ko group again.
Black captures White's single stone in the corner, achieving a living shape for his former bent-four.
at B, ...) aside for a while, as it would only lead us astray in this L&D example.
.