J89's pass-for-ko: Misinterpreted in the Western Go World?

[Cassandra]

I tried to build an example for which this third interpretation may give a result different from J2003 but I am not completly sure.

$$B
$$ +-------------------+
$$ | B B . O X O . O . |
$$ | B B O O X X O O O |
$$ | O O O O X . X O O |
$$ | . O O O X X O O O |
$$ | O Z O O X . X X X |
$$ | Z Z . O X X X O O |
$$ | Z O O O O O O O O |
$$ | . X O X X X X X X |
$$ | X . X . X . . X . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$B
$$ +-------------------+
$$ | B B . O X O . O . |
$$ | B B O O X X O O O |
$$ | O O O O X . X O O |
$$ | . O O O X X O O O |
$$ | O Z O O X . X X X |
$$ | Z Z . O X X X O O |
$$ | Z O O O O O O O O |
$$ | . X O X X X X X X |
$$ | X . X . X . . X . |
$$ +-------------------+[/go]

It would be completely pointless to deliberately and with a vengeance construct differences between sets of rules by using positions that contain a snapshot of "eternal life" before the game stopped.

$$W
$$ +-------------------+
$$ | X X . O X . X X O |
$$ | X X O O X X X O O |
$$ | O O O O X . X O O |
$$ | . O O O X X X O O |
$$ | O Z O O X . X O O |
$$ | Z Z 1 O X X X O O |
$$ | Z O O O O O O O O |
$$ | . X O X X X X X X |
$$ | X . X . X . . X . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$W
$$ +-------------------+
$$ | X X . O X . X X O |
$$ | X X O O X X X O O |
$$ | O O O O X . X O O |
$$ | . O O O X X X O O |
$$ | O Z O O X . X O O |
$$ | Z Z 1 O X X X O O |
$$ | Z O O O O O O O O |
$$ | . X O X X X X X X |
$$ | X . X . X . . X . |
$$ +-------------------+[/go]

Probably you will realise the difference...

[kvasir]

[...]because of the normal ko rule[...]

I see what I misunderstood.

It seems hard to find any support in the English translation for this "pass once" interpretation, but it seems to be as simple as someone just reading the Japanese.

I did also notice when checking the Japanese with google translate that it is evident that the commentary and examples have detail in the English about which ko to pass for were as the Japanese does not. There also appears to be paragraphs in the translation that are not in the Japanese, for example the first paragraph of "2. Positions Related to Article 7, Clauses 1 and 2" doesn't appear to be found in the Japanese. I refer to the version on the NHK web

It is a bit weird if the translation doesn't match the official version, but the matter really just ends there for me because it is really just a question of reading the Japanese, someone making a new translation. There doesn't seem to be anyone who claims their Japanese is very good that is pointing out errors here.

[Cassandra]

I did also notice when checking the Japanese with google translate that it is evident that the commentary and examples have detail in the English about which ko to pass for were as the Japanese does not. ... I refer to the version on the NHK web

From the CURRENT J89 on the Nihon Kiin web:

https://www.nihonkiin.or.jp/match/kiyak ... u07-2.html

[kvasir]

I mentioned this before, this would be referring to the "top corner" and the "bottom corner", but there are 2 ko shapes in the bottom corner and this is distinguished in the English translation. Just browsing through the text should be enough to see that the translation refers to ko-passes by the last move in that shape while the Japanese sometimes refers to the corner or just has an unqualified "pass".

But what is the point of us discussing interpretations of the Japanese? It is one thing to discuss the English translation but as for the Japanese original we better just wait for someone that knows Japanese very well to come along and resolve that.

[Cassandra]

But what is the point of us discussing interpretations of the Japanese? It is one thing to discuss the English translation but as for the Japanese original we better just wait for someone that knows Japanese very well to come along and resolve that.

For now -- deep in the night -- please refer to viewtopic.php?p=267226#p267226 ("old" translation matches the CURRENT Japanese text).

More on J89's commentary section is to come in bright daylight

[Cassandra]

$$B
$$ +---------------------------+
$$ | X O a . X O . . . . . . . |
$$ | . X X X X O . . . . . . . |
$$ | X X O O O O . . . . . . . |
$$ | O O O , . . . . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . , . . . . . . |
$$ | X X X X X . . . . . . . . |
$$ | O O O O X . . . . . . . . |
$$ | X O . O X . . . . , . . . |
$$ | . X O O X X . . . . . . . |
$$ | X X X O O X . . . . . . . |
$$ | . X O . O X . . . . . . . |
$$ +---------------------------+

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------------+
$$ | X O a . X O . . . . . . . |
$$ | . X X X X O . . . . . . . |
$$ | X X O O O O . . . . . . . |
$$ | O O O , . . . . . , . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . . . . , . . . . . . |
$$ | X X X X X . . . . . . . . |
$$ | O O O O X . . . . . . . . |
$$ | X O . O X . . . . , . . . |
$$ | . X O O X X . . . . . . . |
$$ | X X X O O X . . . . . . . |
$$ | . X O . O X . . . . . . . |
$$ +---------------------------+[/go]

A comparison of the translation by James Davies at the time and a translation of the CURRENT version of the comments on the combined formation of a "one-move approach-move-ko" and a "double-ko seki" makes it easy to see what has been adjusted in the meantime.

James Davies' translation	Translation of CURRENT version
3. Approach-move ko with double-ko seki (example of capturing again after passing for that particular ko capture).	3 It is necessary to pass for each of the ko to be recaptured.
./.	If there are two or more ko to be recaptured, it must be specified which one to pass for.
Suppose positions in Diagram 11 are both present on the board. The question is whether the game can end without Black's playing at A.	(1) If the shapes of the upper and lower corners coexist on the board, it is the question of whether or not the game can end without any Black teire at A in the "One-move yose-ko" in the upper corner.
The answer: If the game ends in this way, the white stone is dead despite the double ko in the position at the right. Black does not have to add a stone at A.	(2) If the game ends as it is the conclusion is even if there is a "double-ko seki" in the lower corner, the white stone in the upper corner is a "dead stone", the black eight stones there are "alive stones", and the lower corner remains the same1) "double-ko seki"; therefore, Black doesn't need to teire at A.
The reason the white stone is dead is as follows. White 1 takes ko (on left) and Black 2 passes because recapturing is prohibited except after passing. White 3 gives atari. Black 4 retakes ko, a legal play because Black has passed once for this ko (in lieu of Black 2). White 5 takes a ko on the right and Black 6 takes the other ko. White 7 passes for the left ko, because recapturing without first passing is prohibited. Black 8 captures two white stones on the left. White 9 and Black 10 pass for kos on the right. White 11 takes ko; this is legal because White has passed at play 9. Black 12 takes ko; this is legal because Black has passed at play 10. Note that if White 7 was a pass for the ko 6/11 on the right, Black could have played 8 at 12 and captured the white group on the right. White could still not capture on the left and that Black group would remain alive.	(3) The reason is based on White 1 to Black 12 in Reference Figures 11 <2> to <4>. It is possible to make a new ko-capture with Black 4 in Reference Figure 11 <3> because Black 2 has already passed for the same ko. Black 2 upper corner pass White 7 upper corner pass, White 9 lower corner pass, Black 10 lower corner pass

_________________
¹⁾ This "same" might be the reason for having an entire double-ko cycle in the sequence.

[kvasir]

Your translation and James Davie's are quite different but it is hard to find a "misinterpretation".

It is interesting that example 18 is different (which was pointed out in another thread), I'd say "The plot thickens", but are we to understand that you are working on a new translation?

I'd say that the words that you quote from the translation have some bearing on the ongoing discussions in this and the other threads.

The question is whether the game can end without Black's playing at A.

This can be interpreted to mean that during confirmation (this is actually exactly what I learned when I learned how to play and my experience when playing Japanese persons) the object is not to resolve some bestiary like mutual-death and surprise ko fights but to fill in dame and add defensive moves that could have been added during normal play but the Japanese like to omit. Defensive moves during confirmation are only mentioned in the examples of confirmations, not the rules themselves, but are we not to conclude from this that the players are allowed to make these defensive moves after plays ends and before the "end of the game" (i.e. during confirmation).

[Cassandra]

The question is whether the game can end without Black's playing at A.

This can be interpreted to mean that during confirmation (this is actually exactly what I learned when I learned how to play and my experience when playing Japanese persons) the object is not to resolve some bestiary like mutual-death and surprise ko fights but to fill in dame and add defensive moves that could have been added during normal play but the Japanese like to omit. Defensive moves during confirmation are only mentioned in the examples of confirmations, not the rules themselves, but are we not to conclude from this that the players are allowed to make these defensive moves after plays ends and before the "end of the game" (i.e. during confirmation).

Very interesting experience. Thank you for sharing it.

What you wrote about some Japanese fondness, seems to be backed by J89's commentary on Article 9, "End of the game":


Article 9, clause 2: After the game is stopped, and both sides confirmed the life and death of the stones and the territory, the game ends by agreement. This is called "end of the game".

<Commentary>

1 "Dame-occupation" and "teire" are necessary
In order to confirm the life and death of the stones and the territory according to Article 8, "dame-occupation" and "teire" must be made until the end of the game.

2 After the game has stopped, "dame-occupation" and "teire" are outside regulation
With the agreement of the players, if "dame-occupation" and "teire" is appropriate after the game stopped, they do not fall under the prescribed regulations for "move".


The Japanese understanding of the matter seems only natural, as it makes a FORMAL resumption of the game superfluous in potentially "critical" L&D cases. Which would be possible, as the players have not yet agreed about ending the game. As potential unwanted side-effects of necessary, but still unplayed, "teire" exist during confirmation of L&D ONLY (due to "pass-for-ko"), but not during "play", it will not have any negative effect to have the opponent re-continuing the "normal" game (not unlikely with a "pass").

[Cassandra]

J89's Life and Death Example 18:: "Bent-Four and IRREMOVABLE KO-THREAT"!!! ==> "Dead"

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

The double-ko seki at right can easily lead us on the wrong track, because it is part of this example ONLY because of its quality as a ko-threat that cannot be eliminated.

This example is NOT (!!!) "Bent-Four and Double-Ko Seki", as we will see soon.


+++++++++++++++++++++++++++

Let's examine what would happen during "play".

$$W :b2: pass
$$ +---------------------–-
$$ | 1 O 3 X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | 4 X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W :b2: pass
$$ +---------------------–-
$$ | 1 O 3 X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | 4 X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

attack's Black's bent-four in the corner.

$$W
$$ +---------------------–-
$$ | 6 5 . X O X O . . . .|
$$ | 7 X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------–-
$$ | 6 5 . X O X O . . . .|
$$ | 7 X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

avoids a quick death.
gives atari at Black's corner group.

$$Bm8
$$ +---------------------–-
$$ | 3 O a X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O 1 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 2 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------–-
$$ | 3 O a X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O 1 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 2 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

gives atari in the double-ko. This is the IRREMOVABLE KO-THREAT!!!
also captures in the double-ko.
recaptures in the corner.
This move would NOT be valid during J89's status confirmation, Black would have to play a "pass-for-ko", instead, whereafter White would capture with A.

$$Bm8
$$ +---------------------–
$$ | X O 5 X O X O . . . .|
$$ | b X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O X 4 X X O , .|
$$ | O O O . O X 6 X O . .|
$$ | X X O O a O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------–
$$ | X O 5 X O X O . . . .|
$$ | b X X X O X O O . . .|
$$ | X X O O O X X O O . .|
$$ | X X O O X 4 X X O , .|
$$ | O O O . O X 6 X O . .|
$$ | X X O O a O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

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.
We will leave "chôsei" (i.e. at A, at B, ...) aside for a while, as it would only lead us astray in this L&D example.
captures Black's double-ko group.

$$Bm8
$$ +---------------------–
$$ | X . X X O . O . . . .|
$$ | . X X X O . O O . . .|
$$ | X X O O O . . O O . .|
$$ | X X O O . O . . O , .|
$$ | O O O . O . O . O . .|
$$ | X X O O . O . . O . .|
$$ | . X X O O . . O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------–
$$ | X . X X O . O . . . .|
$$ | . X X X O . O O . . .|
$$ | X X O O O . . O O . .|
$$ | X X O O . O . . O , .|
$$ | O O O . O . O . O . .|
$$ | X X O O . O . . O . .|
$$ | . X X O O . . O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

White was unable to capture the entire corner.

--------------------------------

Variation:

$$Bm8
$$ +-----------------------
$$ | . O 2 X X X O X O . .|
$$ | O X X X O O O X O . .|
$$ | X X X O O X X X O . .|
$$ | X X O O 1 O X X O , .|
$$ | X X O 3 O X . X O . .|
$$ | X X O O X a X X O . .|
$$ | X X X O O X X O O . .|
$$ | X X X O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8
$$ +-----------------------
$$ | . O 2 X X X O X O . .|
$$ | O X X X O O O X O . .|
$$ | X X X O O X X X O . .|
$$ | X X O O 1 O X X O , .|
$$ | X X O 3 O X . X O . .|
$$ | X X O O X a X X O . .|
$$ | X X X O O X X O O . .|
$$ | X X X O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

would capture Black's corner group, if it was much larger.
During J89's status confirmation, White would capture with A in the double-ko.
captures through.

$$Bm8 :w11: pass
$$ +-----------------------
$$ | . O O . . . O X O . .|
$$ | O . . . O O O X O . .|
$$ | . . . O O X X X O . .|
$$ | . . O O X . X X O , .|
$$ | . . O X 5 X . X O . .|
$$ | . . O O X . X X O . .|
$$ | . . . O O X X O O . .|
$$ | . . . O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8 :w11: pass
$$ +-----------------------
$$ | . O O . . . O X O . .|
$$ | O . . . O O O X O . .|
$$ | . . . O O X X X O . .|
$$ | . . O O X . X X O , .|
$$ | . . O X 5 X . X O . .|
$$ | . . O O X . X X O . .|
$$ | . . . O O X X O O . .|
$$ | . . . O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

can only pass.
Black connects the ko, achieving a living shape for his double-ko group.

$$Bm8
$$ +-----------------------
$$ | . O O . . . O X O . .|
$$ | O . . . O O O X O . .|
$$ | . . . O O X X X O . .|
$$ | . . O O X . X X O , .|
$$ | . . O X X X . X O . .|
$$ | . . O O X . X X O . .|
$$ | . . . O O X X O O . .|
$$ | . . . O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$Bm8
$$ +-----------------------
$$ | . O O . . . O X O . .|
$$ | O . . . O O O X O . .|
$$ | . . . O O X X X O . .|
$$ | . . O O X . X X O , .|
$$ | . . O X X X . X O . .|
$$ | . . O O X . X X O . .|
$$ | . . . O O X X O O . .|
$$ | . . . O X O O O . . .|
$$ | O O O O X X X X . . .|
$$ | X X X X X . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

Again, White was unable to capture the entire corner.

In status confirmation, Black would prefer this variation, as is played AFTER his corner group has been captured, providing that group with the status "alive", too.
As we have already stated above, J89's status confirmation would never reach this point.

--------------------------------

You will have realised that White can capture only ONE of both Black groups during "play". Thus, we could anticipate the entire corner becoming a large seki during status confirmation, similar to J89's L&D example 4, if left untouched.

However, Japanese understanding prohibits "real" ko-fights during J89's status confirmation, overriding the results achieved above.
Thus, the entire corner will become White's territory.



+++++++++++++++++++++++++++

$$W
$$ +---------------------------+
$$ | . O . X O X . O O O O O O |
$$ | O X X X O X . O O O O O O |
$$ | . X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . O . X O X . O O O O O O |
$$ | O X X X O X . O O O O O O |
$$ | . X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

Same topic, different position.

--------------------------------

$$W :b2: pass
$$ +---------------------------+
$$ | 1 O 3 X O X . O O O O O O |
$$ | O X X X O X . O O O O O O |
$$ | 4 X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W :b2: pass
$$ +---------------------------+
$$ | 1 O 3 X O X . O O O O O O |
$$ | O X X X O X . O O O O O O |
$$ | 4 X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

attacks Black's bent-four at the left.

$$W
$$ +---------------------------+
$$ | 6 5 . X O X . O O O O O O |
$$ | 7 X X X O X . O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | 6 5 . X O X . O O O O O O |
$$ | 7 X X X O X . O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

$$Bm8
$$ +---------------------------+
$$ | . O 2 X O X 3 O O O O O O |
$$ | O X X X O X 1 O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------------+
$$ | . O 2 X O X 3 O O O O O O |
$$ | O X X X O X 1 O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

gives atari at the right. This is the IRREMOVABLE KO-THREAT!!!
captures at the left here.
captures at the right.
During "status confirmation", this move would provide the captured group at the left with the status "alive".

$$Bm8
$$ +---------------------------+
$$ | . O O . O X X . . . . . . |
$$ | O . . . O X X . . . . . . |
$$ | . . O O O X X X X X X X X |
$$ | . . O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------------+
$$ | . O O . O X X . . . . . . |
$$ | O . . . O X X . . . . . . |
$$ | . . O O O X X X X X X X X |
$$ | . . O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

White could not capture all of Black's groups.

--------------------------------

Variation:

$$Bm8 :w11: pass
$$ +---------------------------+
$$ | 3 O 5 X O X 2 O O O O O O |
$$ | O X X X O X 1 O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$Bm8 :w11: pass
$$ +---------------------------+
$$ | 3 O 5 X O X 2 O O O O O O |
$$ | O X X X O X 1 O O O O O O |
$$ | X X O O O X X X X X X X X |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

captures Black's group at the right.
White would choose this line of play in J89's status confirmation.
Black recaptures at the left.
This move would be unvalid in J89's status confirmation. Black would have to play a "pass-for-ko", instead, whereafter White would capture with .
can only pass.
achieves a living formation.
Again, Black's captured group (here that at the right) would also be "alive" during status confirmation.
J89's status confirmation would NOT reach this point.

$$Bm8
$$ +---------------------------+
$$ | X . X X O . O O O O O O O |
$$ | . X X X O . . O O O O O O |
$$ | X X O O O . . . . . . . . |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$Bm8
$$ +---------------------------+
$$ | X . X X O . O O O O O O O |
$$ | . X X X O . . O O O O O O |
$$ | X X O O O . . . . . . . . |
$$ | X X O X X O O O O O O O O |
$$ | O O O X O O . . . . . . . |
$$ | . . X X O . . . . . . . . |
$$ | X X X O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

Again, White could not capture all of Black's groups.


+++++++++++++++++++++++++++


You will have realised that the double-ko seki in J89's L&D example 18 is NOT an element of this example in its capacity as a double-ko seki as such.
The formation in example 18 probably looks a little less improbable than the one I created.

You will also have understood that "bent-four & irremovable ko-threat" would become seki in status confirmation without any special regulation that prohibits the flare-up of ko-fights.

[kvasir]

$$W
$$ +---------------------------+
$$ | . 7 . 4 3 2 . 1 1 1 1 1 1 |
$$ | 5 4 4 4 3 2 . 1 1 1 1 1 1 |
$$ | . 4 3 3 3 2 2 2 2 2 2 2 2 |
$$ | 4 4 3 6 6 O O O O O O O O |
$$ | 3 3 3 6 O O . . . . . . . |
$$ | . . 6 6 O . . . . . . . . |
$$ | 6 6 6 O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . 7 . 4 3 2 . 1 1 1 1 1 1 |
$$ | 5 4 4 4 3 2 . 1 1 1 1 1 1 |
$$ | . 4 3 3 3 2 2 2 2 2 2 2 2 |
$$ | 4 4 3 6 6 O O O O O O O O |
$$ | 3 3 3 6 O O . . . . . . . |
$$ | . . 6 6 O . . . . . . . . |
$$ | 6 6 6 O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

I don't think this is controversial or unexpected:
seki, seki, alive, dead, alive, dead, alive


But in example 18 it appears that unless pass-ko is limited (for example as Jann suggests) it is unclear why the marked stone is dead.

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

Why is it not alive like this, maybe your translations can shed light on this somehow.

$$W :b4: pass :w5: pass
$$ +---------------------–-
$$ | 1 O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 3 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W :b4: pass :w5: pass
$$ +---------------------–-
$$ | 1 O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 3 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

$$B :b3: pass :w4: pass
$$ +---------------------–-
$$ | O O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 2 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 1 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B :b3: pass :w4: pass
$$ +---------------------–-
$$ | O O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 2 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 1 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

Black appears to always be able to play at again because of the pass-ko.

[Cassandra]

But in example 18 it appears that unless pass-ko is limited (for example as Jann suggests) it is unclear why the marked stone is dead.

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

can be captured, but will be never re-established.

---------------------------

$$W
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 1 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 1 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

$$W :w3: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 5 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 4 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W :w3: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 5 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 4 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

$$W :b6: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 8 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 7 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W :b6: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 8 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 7 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

---------------------------

Variation:

$$W
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 1 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 2 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 1 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

$$W :w3: pass-for-ko; :b4: pass-for-ko; :w5: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 7 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 6 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$W :w3: pass-for-ko; :b4: pass-for-ko; :w5: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X 7 X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O 6 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

Same as above.

[Cassandra]

$$W
$$ +---------------------------+
$$ | . 7 . 4 3 2 . 1 1 1 1 1 1 |
$$ | 5 4 4 4 3 2 . 1 1 1 1 1 1 |
$$ | . 4 3 3 3 2 2 2 2 2 2 2 2 |
$$ | 4 4 3 6 6 O O O O O O O O |
$$ | 3 3 3 6 O O . . . . . . . |
$$ | . . 6 6 O . . . . . . . . |
$$ | 6 6 6 O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . 7 . 4 3 2 . 1 1 1 1 1 1 |
$$ | 5 4 4 4 3 2 . 1 1 1 1 1 1 |
$$ | . 4 3 3 3 2 2 2 2 2 2 2 2 |
$$ | 4 4 3 6 6 O O O O O O O O |
$$ | 3 3 3 6 O O . . . . . . . |
$$ | . . 6 6 O . . . . . . . . |
$$ | 6 6 6 O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

I don't think this is controversial or unexpected:
seki, seki, alive, dead, alive, dead, alive

Sorry, but...

++++++++++++++++++++++++++++++++

Status confirmation WITHOUT any kind of ko ban:

$$W
$$ +---------------------------+
$$ | . W . # W # . W W W W W W |
$$ | W # # # W # . W W W W W W |
$$ | . # W W W # # # # # # # # |
$$ | # # W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . W . # W # . W W W W W W |
$$ | W # # # W # . W W W W W W |
$$ | . # W W W # # # # # # # # |
$$ | # # W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

$$W
$$ +---------------------------+
$$ | . @ . # W # . @ @ @ @ @ @ |
$$ | @ # # # W # . @ @ @ @ @ @ |
$$ | . # W W W # # # # # # # # |
$$ | # # W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . @ . # W # . @ @ @ @ @ @ |
$$ | @ # # # W # . @ @ @ @ @ @ |
$$ | . # W W W # # # # # # # # |
$$ | # # W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

Black's groups in the corners are "alive in seki".
White's groups in the corners are "alive in seki".
White's group that surrounds the bent-four is "alive".
Black's group at the left edge is "dead".

Thus, the region at the left edge is White territory.

--------------------------------

In the case "re-establishment" of captured stones is restricted to the board points that were former occupied by these:

$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

All White groups are "alive".
All Black groups are "dead".


++++++++++++++++++++++++++++++++

J89's status confirmation with "pass-for-ko":

$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

All White groups are "alive".
All Black groups are "dead".

[kvasir]

J89's status confirmation with "pass-for-ko":

$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z . W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

All White groups are "alive".
All Black groups are "dead".

I wasn't sure what your conclusion about the group of white stones in the top-right was. It is seki but you seem to say the opposite that black is dead, but that can only be the case if black had to remove a liberty.

$$B black never plays :b1:
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z 1 W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |

Click Here To Show Diagram Code

[go]$$B black never plays :b1:
$$ +---------------------------+
$$ | . W . Z W Z . W W W W W W |
$$ | W Z Z Z W Z 1 W W W W W W |
$$ | . Z W W W Z Z Z Z Z Z Z Z |
$$ | Z Z W Z Z O O O O O O O O |
$$ | W W W Z O O . . . . . . . |
$$ | . . Z Z O . . . . . . . . |
$$ | Z Z Z O O . , . . , . . . |
$$ | O O O O . . . . . . . . . |
$$ | . . . . . . . . . . . . . |
$$ | . . . , . . , . . , . . . |[/go]

But in example 18 it appears that unless pass-ko is limited (for example as Jann suggests) it is unclear why the marked stone is dead.

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O Y . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

can be captured, but will be never re-established.

OK. I realized that the rules are quite clear on this stone being dead. "Life-and-Death Example 25: Double-Ko Seki" also explains that the ko stones in double-ko are dead because they can always be recaptured, so that is clear.

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . W X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . W X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

If this is the case then why isn't the marked stone dead? Same argument as before, pass-ko allows black to recapture the ko indefinitely.

This example seems to get to the core of the pass-ko interpretation.

[Cassandra]

$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . W X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O . W X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X . X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|
$$ | . . . . . . . . . . .|[/go]

If this is the case then why isn't the marked stone dead? Same argument as before, pass-ko allows black to recapture the ko indefinitely.

This example seems to get to the core of the pass-ko interpretation.

$$B :b3: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 1 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 2 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B :b3: pass
$$ +---------------------–-
$$ | . O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O 1 O X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O X 2 X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|[/go]

$$B
$$ +---------------------–-
$$ | 4 O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X C X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O . O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | 4 O . X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X C X X O , .|
$$ | O O O . O X . X O . .|
$$ | X X O O . O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|[/go]

Thereafter, White kills everything in the corner under J89.

will become again.

It's a bit tricky, I know. But there can be different sequences for different groups under consideration.

[kvasir]

It's a bit tricky, I know. But there can be different sequences for different groups under consideration.

If there are two different determinations for the same stone, it is actually not "tricky" it is "indeterminate".

You had this diagram and I add some moves, noting that while black did pass for the ko, white didn't and therefore can't retake.

$$B
$$ +---------------------–-
$$ | 4 O 6 X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X . X X O , .|
$$ | O O O 7 O X . X O . .|
$$ | X X O O 5 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------–-
$$ | 4 O 6 X O X O . . . .|
$$ | O X X X O X O O . . .|
$$ | . X O O O X X O O . .|
$$ | X X O O X . X X O , .|
$$ | O O O 7 O X . X O . .|
$$ | X X O O 5 O X X O . .|
$$ | . X X O O X X O O . .|
$$ | . . X X X O O O . . .|
$$ | . . . . X X X X . . .|
$$ | . . . , . . . . . , .|
$$ | . . . . . . . . . . .|[/go]

Basically, if white had passed for a ko then couldn't have been played. This line of reasoning does obviously not match the determination in the examples. Anyway, we did discus some possible reasons already.