Moonlight life and go rules

[Pio2001]

$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

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]

$$W White to play
$$ --------------
$$ | O X 1 X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

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]

pass
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!

Hi Gérard,
In article 10 of AGA rules, after resumption, it is said that "If they both pass while a disagreement still exists, all stones remaining on the board are alive, and the board in counted as it stands".

[Mike Novack]

Sorry, but I keep looking at that and can't see how the final position cold have been reached (in ko) EXCEPT by black having passed after white had made a self atari move.

Care to present the last half dozen moves or so instead of just the final position. Say from a couple moves before the two black stones were captured.

[Gérard TAILLE]

Sorry, but I keep looking at that and can't see how the final position cold have been reached (in ko) EXCEPT by black having passed after white had made a self atari move.

Care to present the last half dozen moves or so instead of just the final position. Say from a couple moves before the two black stones were captured.

Oops I do not see what is really your problem. Anyway here is an example of game (without any pass)

[Cassandra]

I am afraid that the style of your "game" sequence might be very infantile.

Black has had numerous chances to win that game by 25 points. Therefore -- at this childish level of understanding of the game -- it does not matter, whether White's group might be alive (but without any territory), resulting in a Black win by 13 points "only". Black will be happy to count the Smarties he got for free during the game.

I can't get rid of the feeling that this kind of discussion is comparable to that about an AI who is supposed to solve a task for which it has not been trained.
Neither must the AI be blamed for her poor performance, nor a rule set for not giving a 100%-answer to a question that is has never be designed for.

[Gérard TAILLE]

$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

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]

AGA rule : we saw that in the position above white can live by taking the ko. That's true but it does not look to be in the spirit of the go game. Comparing to japonese rule this result is due to the fact that, when in AGA rule the play is resumed after two passes, all the ko bans (superko) are not lifted. Do you know if it was a real choice of the rule (in order to avoid adding some complexity to the rule)?

[Gérard TAILLE]

I am afraid that the style of your "game" sequence might be very infantile.

Black has had numerous chances to win that game by 25 points. Therefore -- at this childish level of understanding of the game -- it does not matter, whether White's group might be alive (but without any territory), resulting in a Black win by 13 points "only". Black will be happy to count the Smarties he got for free during the game.

I can't get rid of the feeling that this kind of discussion is comparable to that about an AI who is supposed to solve a task for which it has not been trained.
Neither must the AI be blamed for her poor performance, nor a rule set for not giving a 100%-answer to a question that is has never be designed for.

I agree with you but the purpose here was not to play good or bad moves but only to consider pure theoritical point concerning the rule. In itself the game I showed is really completly stupid in practice but the point was only to show that the final position can be reach with legal play.
Obviously I did not understand correctly Mike Novack issue. Sorry for that.

[jann]

Comparing to japonese rule this result is due to the fact that, when in AGA rule the play is resumed after two passes, all the ko bans (superko) are not lifted. Do you know if it was a real choice of the rule (in order to avoid adding some complexity to the rule)?

It is very hard for pass to lift bans under superko as this breaks the essence of superko and reinstates most problems it tried to solve (like sending2-returning1 abuse for area scoring).

[Cassandra]

but the point was only to show that the final position can be reach with legal play.

"Legal" play ALONE is not sufficient for a discussion of rule sets at the very high level that you apparently intend to do.

Utilising positions that can be reached only after several "infantile" mistakes (of both sides) cannot be the right method for qualified discussions at a "professional" level. Intending to do so disqualifies yourself.

[Gérard TAILLE]

but the point was only to show that the final position can be reach with legal play.

"Legal" play ALONE is not sufficient for a discussion of rule sets at the very high level that you apparently intend to do.

Utilising positions that can be reached only after several "infantile" mistakes (of both sides) cannot be the right method for qualified discussions at a "professional" level. Intending to do so disqualifies yourself.

Does that mean you do not like unrealistic problems for which the initial position can be reached only by several "infantile" mistakes ?

[lightvector]

Comparing to japonese rule this result is due to the fact that, when in AGA rule the play is resumed after two passes, all the ko bans (superko) are not lifted. Do you know if it was a real choice of the rule (in order to avoid adding some complexity to the rule)?

It is very hard for pass to lift bans under superko as this breaks the essence of superko and reinstates most problems it tried to solve (like sending2-returning1 abuse for area scoring).

This was solved years and years ago by our very own Bill Spight, no? Consider the condition "the game ends if the same player passes in a position in which that player passed before". It is easy to see how even if passes lift ko bans, that this rule still mathematically guarantees that the game is finite. It handles sending-two-returning one fine. And it even can be justified intuitively: "even when passes lift ko bans, if when I pass you have nothing better to do than cycle back the same position where I can pass yet again, clearly you have nothing you can accomplish, so the game should be over".

Depending on what you are trying to accomplish (e.g. if you want to have agreement phases or other details of game end procedure), maybe you can also consider variants. But the key essence is the condition "same player passes in a position where that player passed before".

[Cassandra]

but the point was only to show that the final position can be reach with legal play.

"Legal" play ALONE is not sufficient for a discussion of rule sets at the very high level that you apparently intend to do.

Utilising positions that can be reached only after several "infantile" mistakes (of both sides) cannot be the right method for qualified discussions at a "professional" level. Intending to do so disqualifies yourself.

Does that mean you do not like unrealistic problems for which the initial position can be reached only by several "infantile" mistakes ?

Dear Gérard,

Why do you want to apply a ruleset that was once designed for the real world to "unrealistic" (= irreal) problems?
Do you really think you can prove anything with this attitude?

Let's return to Michael's question with regard to the position below:

$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

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]

In principle, Michael simply asked to show him Black's last move (NO pass).

$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | 1 O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X ? O |
$$ -------------

Click Here To Show Diagram Code

[go]$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | 1 O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X ? O |
$$ -------------[/go]

Why not here???

Otherwise (pass allowed), we have to ask for White's last move.

$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

Click Here To Show Diagram Code

[go]$$W White to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]

E.g. here??? Did White really sacrifice a stone to worsen her score???

$$W Black to play
$$ --------------
$$ | O X . X X |
$$ | 2 O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

Click Here To Show Diagram Code

[go]$$W Black to play
$$ --------------
$$ | O X . X X |
$$ | 2 O X X X |
$$ | O O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]

Black might want to refuse the sacrifice, at least to show some sportsmanship.

If not, we have to ask for Black's last move again.

$$B Black to play
$$ --------------
$$ | O ? O X X |
$$ | . O X X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

Click Here To Show Diagram Code

[go]$$B Black to play
$$ --------------
$$ | O ? O X X |
$$ | . O X X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]

Why not here???

$$B Black to play
$$ --------------
$$ | O X . X X |
$$ | . O ? X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

Click Here To Show Diagram Code

[go]$$B Black to play
$$ --------------
$$ | O X . X X |
$$ | . O ? X X |
$$ | 1 O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]

Or here???

$$B Black to play
$$ --------------
$$ | O X 1 X X |
$$ | . O ? X X |
$$ | . O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------

Click Here To Show Diagram Code

[go]$$B Black to play
$$ --------------
$$ | O X 1 X X |
$$ | . O ? X X |
$$ | . O X X X |
$$ | X X X . X |
$$ | X X X X . |
$$ -------------[/go]

Or here???

[Gérard TAILLE]

Dear Cassandra,

$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | 1 O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X ? O |
$$ -------------

Click Here To Show Diagram Code

[go]$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | 1 O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X ? O |
$$ -------------[/go]

Why not here???

$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X a O |
$$ -------------

Click Here To Show Diagram Code

[go]$$B BLACK to play
$$ --------------
$$ | O X . X X |
$$ | . O X X X |
$$ | O O X X X |
$$ | X X X O X |
$$ | X X X a O |
$$ -------------[/go]

Seeing you accept to envisage what could be a black move in this position, let's start with this position.
If black plays at "a" we reach the position I proposed, right? But you do not want to analyse this position because of "infantile" mistake. Instead you point move "b" as the correct move and I agree with you. But how do you manage to eliminate a black move at "a" without analysing the resulting position? Isn't it a natural move to analyse? How can you decide that a move is an "infantile" mistake without analysing the resulting position?

[Mike Novack]

Sorry, but I keep looking at that and can't see how the final position cold have been reached (in ko) EXCEPT by black having passed after white had made a self atari move.

Care to present the last half dozen moves or so instead of just the final position. Say from a couple moves before the two black stones were captured.

Oops I do not see what is really your problem. Anyway here is an example of game (without any pass)

Misunderstanding. I was referring to the FIRST example, not any later ones (where there would be a variety of methods to reach the final position.

The first has exactly two "cases" for when there are still the initial two black stones present.

a) white has filled such that the only two dame left touch those stones (black has been passing as white has been placing stones. white fills one of them placing the two black stones into atari. BUT that is self atari. I am willing to accept black being infantile, but are you requiring black to also pass in THIS situation instead of capturing all the while stones?
b) White has filled such that there is one dame somewhere else (it does NOT matter where) and one adjacent to the two black stones. Then there are two laces white can play:
1) Fill the external dame --- see "a" You are requiring black to pass while white is in self atari
2) fill the internal dame capturing the two black stones. Now if black plays back in it is NOT atari. White is alive, need not capture but can at the cost of a point -- black has no legal play in either case.

In other words, I will allow you stupid/infantile moves to reach the positions but not obviously willful suicide like failing to notice that the opponent is in self atari. Of course, that COULD be a ko threat << give up a seki to win a larger ko >>

[Gérard TAILLE]

Sorry, but I keep looking at that and can't see how the final position cold have been reached (in ko) EXCEPT by black having passed after white had made a self atari move.

Care to present the last half dozen moves or so instead of just the final position. Say from a couple moves before the two black stones were captured.

Oops I do not see what is really your problem. Anyway here is an example of game (without any pass)

Misunderstanding. I was referring to the FIRST example, not any later ones (where there would be a variety of methods to reach the final position.

The first has exactly two "cases" for when there are still the initial two black stones present.

a) white has filled such that the only two dame left touch those stones (black has been passing as white has been placing stones. white fills one of them placing the two black stones into atari. BUT that is self atari. I am willing to accept black being infantile, but are you requiring black to also pass in THIS situation instead of capturing all the while stones?
b) White has filled such that there is one dame somewhere else (it does NOT matter where) and one adjacent to the two black stones. Then there are two laces white can play:
1) Fill the external dame --- see "a" You are requiring black to pass while white is in self atari
2) fill the internal dame capturing the two black stones. Now if black plays back in it is NOT atari. White is alive, need not capture but can at the cost of a point -- black has no legal play in either case.

In other words, I will allow you stupid/infantile moves to reach the positions but not obviously willful suicide like failing to notice that the opponent is in self atari. Of course, that COULD be a ko threat << give up a seki to win a larger ko >>

I agree with you Mike. The moves needed to reach the position are really completly stupid. No doubt about that. No dispute on my part on this point.
But remember that my intention was to discuss a point in the rule by only using legal moves.
In this specific context do you agree with my point?

[Gérard TAILLE]

Comparing to japonese rule this result is due to the fact that, when in AGA rule the play is resumed after two passes, all the ko bans (superko) are not lifted. Do you know if it was a real choice of the rule (in order to avoid adding some complexity to the rule)?

It is very hard for pass to lift bans under superko as this breaks the essence of superko and reinstates most problems it tried to solve (like sending2-returning1 abuse for area scoring).

This was solved years and years ago by our very own Bill Spight, no? Consider the condition "the game ends if the same player passes in a position in which that player passed before". It is easy to see how even if passes lift ko bans, that this rule still mathematically guarantees that the game is finite. It handles sending-two-returning one fine. And it even can be justified intuitively: "even when passes lift ko bans, if when I pass you have nothing better to do than cycle back the same position where I can pass yet again, clearly you have nothing you can accomplish, so the game should be over".

Depending on what you are trying to accomplish (e.g. if you want to have agreement phases or other details of game end procedure), maybe you can also consider variants. But the key essence is the condition "same player passes in a position where that player passed before".

It is a good idea, but I you say "the game ends if the same player passes in a position in which that player passed before" then you have to change the dispute article of the rule (AGA rule). Take the following basic (stupid) example:

$$B Black to play
$$ ------------
$$ | O . O O O |
$$ | . O O O O |
$$ | O O O O O |
$$ | O O O O . |
$$ | O O O O X |
$$ -------------

Click Here To Show Diagram Code

[go]$$B Black to play
$$ ------------
$$ | O . O O O |
$$ | . O O O O |
$$ | O O O O O |
$$ | O O O O . |
$$ | O O O O X |
$$ -------------[/go]

Black passes (no choice)
White passes also and designs the black stone as being dead.

Assume black does not agree! The game is resumed with black to play and black passes again and now the game ends because black has passed twice in the same situation! The black stones cannot be capture and black was right to dispute the result.