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 Post subject: Moonlight life and go rules
Post #1 Posted: Tue Jul 06, 2021 3:20 am 
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Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]


Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X 1 X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]
:b2: pass
:w3: pass

What is the reult of the game after the two passes, depending of the rule ?
For japonese rule it seems clear that white group is dead.
But what about Chinese and AGA rules?

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 Post subject: Re: Moonlight life and go rules
Post #2 Posted: Tue Jul 06, 2021 6:11 am 
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In an informal game with informal rules clearly the white group is dead. Black has two eyes and white cannot make two eyes or seki.

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 Post subject: Re: Moonlight life and go rules
Post #3 Posted: Tue Jul 06, 2021 6:51 am 
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AGA makes this alive I think. Chinese with its special ko rule probably doesn't.

The question is OC whether ko can be retaken after pass.

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 Post subject: Re: Moonlight life and go rules
Post #4 Posted: Thu Jul 08, 2021 9:34 am 
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jann wrote:
AGA makes this alive I think. Chinese with its special ko rule probably doesn't.

The question is OC whether ko can be retaken after pass.


Yes Jann, I am not sure of my understanding of japonese rule concerning ko after one or two passes:

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


Let's assume it happens :
Click Here To Show Diagram Code
[go]$$W White to play
$$ ------------
$$ | O X 1 X . .
$$ | . O X X . .
$$ | O O X X . .
$$ | X X X . . .
$$ | . . . . . .
$$[/go]
:b2: pass
:w3: pass

Edit: The question is a pure therotical question on the rule. After the two passes is black allowed to resume the game? If yes I suppose it is white to play first, and white pass again! Now, can Black retake the ko and continue "normally" the game? It looks quite unclear for me when reading the rule.

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 Post subject: Re: Moonlight life and go rules
Post #5 Posted: Thu Jul 08, 2021 11:09 am 
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Japanese rules may be relatively problem-free here (as most rules except strict superko). IIRC resumption is defined and should be possible.

Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

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 Post subject: Re: Moonlight life and go rules
Post #6 Posted: Thu Jul 08, 2021 2:12 pm 
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jann wrote:
Japanese rules may be relatively problem-free here (as most rules except strict superko). IIRC resumption is defined and should be possible.

Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The only reference to "resumption" I found in the rule is in the Article 9.3:

3. If a player requests resumption of a stopped game, his opponent must oblige and has the right to play first.

This is not a defintion of resumption and thus the rule seems to me really unclear on that point (I mean retaking a ko immediatly after pass moves), even if I undersatng your guessing.

What is really the purpose of the resumption? Is it only for resolving some disagreements between the two players on the status of some group of stones, or could it be really a strategic mean to retake a ko by using a pass as a ko threat?

Any other ideas from other experts on japonese rule?

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 Post subject: Re: Moonlight life and go rules
Post #7 Posted: Fri Jul 09, 2021 2:15 am 
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Gérard TAILLE wrote:
jann wrote:
Japanese rules may be relatively problem-free here (as most rules except strict superko). IIRC resumption is defined and should be possible.

Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The only reference to "resumption" I found in the rule is in the Article 9.3:

3. If a player requests resumption of a stopped game, his opponent must oblige and has the right to play first.

This is not a defintion of resumption and thus the rule seems to me really unclear on that point (I mean retaking a ko immediatly after pass moves), even if I undersatng your guessing.

What is really the purpose of the resumption? Is it only for resolving some disagreements between the two players on the status of some group of stones, or could it be really a strategic mean to retake a ko by using a pass as a ko threat?

Any other ideas from other experts on japonese rule?


Let's take the following non uncommon situation

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


The common understanding here is that it is locally a seki, and globally both player have an infinity of ko threats.
If now you are allowed to use a pass as a ko threat, and assuming neither player can afford to loose her group, then the game cannot be stopped and we will reach a no result game. That means that the game has changed completly doesn't it?
If it is true then you have to conclude that the ressumption of the game means that you resume the game by just ignoring the last two passes. That way you cannot retake the ko and the result of the position is what is expected (seki and an infinite number of ko threats for both players).

Not clear what the good interpretation is!

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 Post subject: Re: Moonlight life and go rules
Post #8 Posted: Fri Jul 09, 2021 6:29 am 
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Gérard TAILLE wrote:
If now you are allowed to use a pass as a ko threat, and assuming neither player can afford to loose her group, then the game cannot be stopped and we will reach a no result game.

Cannot be stopped? Two passes always stop the game (periodically in case of more than one resumption).

No result would mean there is a repetition that neither player can deviate from. This is not the case here (only one side tries to prolong). And there is no real repetition, since the number of resumption requests cannot be infinite (otherwise the losing player would always request resumption in any position). This is also not explicitly spelled out but seems trivial.

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 Post subject: Re: Moonlight life and go rules
Post #9 Posted: Fri Jul 09, 2021 7:08 am 
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jann wrote:
Gérard TAILLE wrote:
If now you are allowed to use a pass as a ko threat, and assuming neither player can afford to loose her group, then the game cannot be stopped and we will reach a no result game.

Cannot be stopped? Two passes always stop the game (which could happen periodically in case of more than one resumptions).

No result would mean there is a repetition that neither player can deviate from. This is not the case here (only one side tries to prolong). And there is no real repetition, since the number of resumption requests cannot be infinite (otherwise the losing player would always request resumption, in any position). This is also not explicitly spelled out but still seems trivial.


My understanding is the following (maybe I am wrong): after two passes any player can always request a resumption of the game. In that case the opponent player will play first. If this first player do not pass the game continue normally.
What happens if the first player passes? If the second player passes again then the game is definetly stopped (I mean no new resumption is possible).
Otherwise the game continue normally (I mean a new resumption may happen later).

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

Assume for example black to play and black is behind in the game

Click Here To Show Diagram Code
[go]$$B Black to play
$$ ----------------
$$ | . O X 2 X O . .
$$ | O O O X X O . .
$$ | 1 O X X O O . .
$$ | O X . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$[/go]
:b3: pass
:w4: pass
after the two passes, black can request a resumption and white plays first and passes:

:w6: pass
now if black is allowed to retake the ko then
Click Here To Show Diagram Code
[go]$$Bcm7 Black to play
$$ ----------------
$$ | . O 1 O X O . .
$$ | O O O X X O . .
$$ | X O X X O O . .
$$ | 2 X . X O . . .
$$ | X X X X O . . .
$$ | O O O O O . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$[/go]
:b9: pass
:w10: pass
and what in the rule prevents black to resume again the game?
If nothing exists in the rule then we have a loop which implies a no result game.

Edit : it looks like a superko but superko is not handled here in japonese rule.

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 Post subject: Re: Moonlight life and go rules
Post #10 Posted: Fri Jul 09, 2021 7:32 am 
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Gérard TAILLE wrote:
and what in the rule prevents black to resume again the game?
...
What happens if the first player passes? If the second player passes again then the game is definetly stopped (I mean no new resumption is possible).

I never heard of such rule (4 passes) in Japanese rules. Again, AFAIK it is not explicitly spelled out where and how the limit is (can resume 1 time, 10 times or what), but obviously B can not request resumption an infinite times. Otherwise in any normal end position the losing side would resume infinitely.

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 Post subject: Re: Moonlight life and go rules
Post #11 Posted: Fri Jul 09, 2021 7:45 am 
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jann wrote:
Gérard TAILLE wrote:
and what in the rule prevents black to resume again the game?
...
What happens if the first player passes? If the second player passes again then the game is definetly stopped (I mean no new resumption is possible).

I never heard of such rule (4 passes) in Japanese rules. Again, AFAIK it is not explicitly spelled out where and how the limit is (can resume 1 time, 10 times or what), but obviously B can not request resumption an infinite times. Otherwise in any normal end position the losing side would resume infinitely.


OC I agree that the resumption procedure is not very well defined ;-)
Without knowing what is the correct interpretation, do you agree that, in any case, the loop cannot exist if the pass cannot be considered as a ko threat?
Do you know what was really the purpose of the resumption procedure (at the time the rule has been written i.e. in 1989)? What was the problem to solve?

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 Post subject: Re: Moonlight life and go rules
Post #12 Posted: Fri Jul 09, 2021 8:17 am 
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jann wrote:
Gérard TAILLE wrote:
and what in the rule prevents black to resume again the game?
...
What happens if the first player passes? If the second player passes again then the game is definetly stopped (I mean no new resumption is possible).

I never heard of such rule (4 passes) in Japanese rules. Again, AFAIK it is not explicitly spelled out where and how the limit is (can resume 1 time, 10 times or what), but obviously B can not request resumption an infinite times. Otherwise in any normal end position the losing side would resume infinitely.


I have already seen these 4 passes in https://senseis.xmp.net/?Flower%2FUnlimitedPhases but I do not know the value of such article for the official rule.

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 Post subject: Re: Moonlight life and go rules
Post #13 Posted: Fri Jul 09, 2021 8:18 am 
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Gérard TAILLE wrote:
do you agree that, in any case, the loop cannot exist if the pass cannot be considered as a ko threat?

Not without a 4-pass rule, which is (AFAIK) nonexistent in Japanese. The "loop" would still work without making any board play, just requesting resumption again and again, in any position.

Even with a 4-pass rule no pass as ko threat would contradict hypothetical play and would raise the original 1-eye problem. That is not the correct direction.

Quote:
Do you know what was really the purpose of the resumption procedure (at the time the rule has been written i.e. in 1989)?

I don't know the specifics but I think resumption exists in most rulesets and is rather common. For Japanese it may be especially important since it must be able to reach a position that is acceptably scorable. So missed moves, forgotten teire, "changed my mind" or whatever reason adding few moves after an earlier pass can affect LD and hypothetical play as well.

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 Post subject: Re: Moonlight life and go rules
Post #14 Posted: Fri Jul 09, 2021 8:54 am 
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jann wrote:
Even with a 4-pass rule no pass as ko threat would contradict hypothetical play and would raise the original 1-eye problem. That is not the correct direction.


Oops I am not talking about "hypothetical play". I am talking only about the "normal" play. If I understand correctly, when resumption occurs the game continue normally. The hypothetical play begins only after the end of "normal" play i.e. after two passes and with no more resumption.

The only concerns with the rule is to understand how we can avoid a loop due to resumption.
I perfectly know that the rule do not mentionned 4 passes. It is only common sense: if you request resumption but you only pass (after a new pass of your opponent) then the "normal" game is over and "hypothetical play" may begin.
Without this 4 passes (here again I know it is not specified explicitly in the rule) you have to specify when you decide a resumption is no more allowed. What would be your proposal?

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 Post subject: Re: Moonlight life and go rules
Post #15 Posted: Fri Jul 09, 2021 9:10 am 
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Gérard TAILLE wrote:
Oops I am not talking about "hypothetical play". I am talking only about the "normal" play.

I understand, but I doubt you can have a different opinion about whether passes work as a ko threat in one and in the other.

Quote:
you have to specify when you decide a resumption is no more allowed. What would be your proposal?

I don't have have, except using common sense (no infinite resumptions).

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 Post subject: Re: Moonlight life and go rules
Post #16 Posted: Fri Jul 09, 2021 9:46 am 
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jann wrote:
Gérard TAILLE wrote:
Oops I am not talking about "hypothetical play". I am talking only about the "normal" play.

I understand, but I doubt you can have a different opinion about whether passes work as a ko threat in one and in the other.

Quote:
you have to specify when you decide a resumption is no more allowed. What would be your proposal?

I don't have have, except using common sense (no infinite resumptions).


That makes sense for me Jann.
If I where referee I think I will act as follows:
1) OK to say that a ko can be retaken after a pass
2) A resumption of the game cannot occur in a position for which a resumption has already occured previouly in the game.

I know that it is not mentionned like this in the rule, I know also that the point 2) above looks like avoiding a superko (which is not part in japonese rule) but at least it seems both logical and in the spirit of the rule.
Do you agree Jann?

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 Post subject: Re: Moonlight life and go rules
Post #17 Posted: Fri Jul 09, 2021 10:08 am 
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This is the realm of personal preferences. It can also be said avoiding complicated superko-like concepts is one of the advantages (and the spirit) of Japanese.

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 Post subject: Re: Moonlight life and go rules
Post #18 Posted: Tue Jul 13, 2021 3:42 am 
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Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]


Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X 1 X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]
:b2: pass
:w3: pass

Assume AGA rule is used. Whites stones are alive.
In this context what is the correct wording for the status of white group? It doesn't seem to be a seki with another black group (without two eyes) and, in addition, a seki implies at least one neutral point. It is neither an unconditional living group with two eyes is it? May be we can say it is a living group by miracle!

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 Post subject: Re: Moonlight life and go rules
Post #19 Posted: Tue Jul 13, 2021 8:50 am 
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Gérard TAILLE wrote:
Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]


Click Here To Show Diagram Code
[go]$$W White to play
$$ --------------
$$ | O X 1 X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]
:b2: pass
:w3: pass

What is the reult of the game after the two passes, depending of the rule ?
For japonese rule it seems clear that white group is dead.
But what about Chinese and AGA rules?


Under all modern professional rules, White is dead. Under AGA rules, White is alive in a kind of moonshine life. Moonshine life has been controversial in go history. The original position that sparked the controversy is unknown, but apparently required White to have a double ko for an infinite supply of ko threats.

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 Post subject: Re: Moonlight life and go rules
Post #20 Posted: Tue Jul 13, 2021 9:29 am 
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Gérard TAILLE wrote:
jann wrote:
Japanese rules may be relatively problem-free here (as most rules except strict superko). IIRC resumption is defined and should be possible.

Whether the ko can be retaken after pass (in normal play) is not completely clear but may be guessed as passing for a ko (then retake it) is also the basis in hypothetical play.

The only reference to "resumption" I found in the rule is in the Article 9.3:

3. If a player requests resumption of a stopped game, his opponent must oblige and has the right to play first.

This is not a defintion of resumption and thus the rule seems to me really unclear on that point (I mean retaking a ko immediatly after pass moves), even if I undersatng your guessing.

What is really the purpose of the resumption? Is it only for resolving some disagreements between the two players on the status of some group of stones, or could it be really a strategic mean to retake a ko by using a pass as a ko threat?

Any other ideas from other experts on japonese rule?


The Japanese 1949 rules had been criticized for being illogical and having special rulings. The Japanese 1989 rules provide a rationale for its rulings in hypothetical play. Historically the Japanese rules have required agreement about the life and death of stones left on the board. Hypothetical play is one way of reaching agreement about their status. However, in the case of disagreement, another possibility is actual play. Hence, the article about resumption. But it is possible that the life or death of stones depends upon who plays first, and that is why the players do not agree. That is why the player who requests resumption must allow his opponent to play first. Neither player is allowed to benefit from the discussion about hypothetical play. In theory, both players could lose. :shock: :lol:

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