Under japanese rule I guess a white move at "b" cannot better than a white move at "a".
But what about area scoring rules with superko rule?
Can you build in the marked area, an environment such that the best move is a white move at "b" ?
A challenge for all those interesting by curious results.
Curious result in area scoring rule.
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
-
Criado
- Beginner
- Posts: 16
- Joined: Sat Apr 03, 2021 9:05 am
- Rank: Tygem 2d
- GD Posts: 0
- Been thanked: 2 times
Re: Curious result in area scoring rule.
I tried to no avail. It is easy to find a position where b is as good as a, but not strictly better. I hoped it had to use some of these cool ideas about the forcing pass lemma but I can't fit it in this board. With larger options for a and b I think it is doable.
Do you have a solution?
Do you have a solution?
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
Re: Curious result in area scoring rule.
Here is my solution (I hope it works well):Criado wrote:I tried to no avail. It is easy to find a position where b is as good as a, but not strictly better. I hoped it had to use some of these cool ideas about the forcing pass lemma but I can't fit it in this board. With larger options for a and b I think it is doable.
Do you have a solution?
-
kvasir
- Lives in sente
- Posts: 1040
- Joined: Sat Jul 28, 2012 12:29 am
- Rank: panda 5 dan
- GD Posts: 0
- IGS: kvasir
- Has thanked: 25 times
- Been thanked: 187 times
Re: Curious result in area scoring rule.
Please explain.
As far as I can tell white can get 4 of the marked intersections and it doesn't appear to matter which is played first. What does superko have to do with it? For example
As far as I can tell white can get 4 of the marked intersections and it doesn't appear to matter which is played first. What does superko have to do with it? For example
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
Re: Curious result in area scoring rule.
The point is that white can get 5 of the marked intersections by: because black would have no move after: Compare with the sequence where black can play the movekvasir wrote:Please explain.
As far as I can tell white can get 4 of the marked intersections and it doesn't appear to matter which is played first. What does superko have to do with it? For example
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
Re: Curious result in area scoring rule.
I do not know.kvasir wrote:I see.
Why again doesn't pass lift superko?
I agree with you. I have the same question.
Re: Curious result in area scoring rule.
Because then it wouldn't protect area scoring from all unbalanced repetition (like the non-ko line in sending3-returning1). Also the whole idea of superko is to look for position changes (instead of elapsed time as with normal ko, ie. no immediate recapture).Gérard TAILLE wrote:I do not know.kvasir wrote:Why again doesn't pass lift superko?
I agree with you. I have the same question.
-
kvasir
- Lives in sente
- Posts: 1040
- Joined: Sat Jul 28, 2012 12:29 am
- Rank: panda 5 dan
- GD Posts: 0
- IGS: kvasir
- Has thanked: 25 times
- Been thanked: 187 times
Re: Curious result in area scoring rule.
Ok. Preventing unbalanced repetition then is the reason.
Maybe there is a good definition somewhere of what a superko is and what it is not? I'd be perfectly happy with a strict definition but Sensei's library on one hand seems to allow for almost anything when it says (https://senseis.xmp.net/?Superko):
Off topic, doubly off topic I guess, but elsewhere on SL it is claimed that ING rules have superko. This seems odd to me, maybe "hot stones" are the "circumstance". Next one could try to argue that the basic ko rule forbids "repetition of an earlier board position under certain circumstances", the specific circumstances have something to do with ko shapes in the position.
Maybe there is a good definition somewhere of what a superko is and what it is not? I'd be perfectly happy with a strict definition but Sensei's library on one hand seems to allow for almost anything when it says (https://senseis.xmp.net/?Superko):
Pass is even discussed as something affecting superko in that article. Pass is a "circumstance", so this can be allowed with the SL definition.Superko rules prohibit recurrences of an earlier board position under certain circumstances.
Off topic, doubly off topic I guess, but elsewhere on SL it is claimed that ING rules have superko. This seems odd to me, maybe "hot stones" are the "circumstance". Next one could try to argue that the basic ko rule forbids "repetition of an earlier board position under certain circumstances", the specific circumstances have something to do with ko shapes in the position.
-
lightvector
- Lives in sente
- Posts: 759
- Joined: Sat Jun 19, 2010 10:11 pm
- Rank: maybe 2d
- GD Posts: 0
- Has thanked: 114 times
- Been thanked: 916 times
Re: Curious result in area scoring rule.
If you want to avoid this kind of pathology, but still break all cycles, guarantee that games are finite, and handle the "basic" situations the way that most players' intuitions think they should be handled (of course there are always still more complex rules beasts), you can use Bill Spight's innovation regarding ko bans and game end:
Use a superko rule as normal, except:
1. Passes lift all ko bans (superko only stops repetitions where neither player passed in between).
2. Regardless of what passes occur in between or not, the game ends when a player passes in a position that player previously passed in. (and this is the only game end condition now. So in normal games it means that the game usually ends with 3 consecutive passes, not 2).
#1 is of course targeted at breaking the kinds of positions in this thread.
Intuition for #2 is to say that even if ko bans are lifted, we can still end the game in the case of cycles involving enough passes, because passes usually indicate one or both players have nothing better to do.
In normal cases with 3 passes, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 passes: "I have nothing I want to do, not even with ko bans lifted"
P1 passes: "I have nothing I want to do, not even with ko bans lifted - okay the game should end since neither player has useful things to do".
In cases with unbalanced repetition where only 1 player is passing while the other player cycles, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 plays some moves that force P1 to respond, but they only lead back to the same position where P1 passes originally.
P1 passes: "I still have nothing I want to do, and if the best that you, P2, could do even with all ko bans lifted and a free extra turn was merely to cycle back to the same position where I can pass yet again, then obviously you're just wasting time, the game should end now."
Use a superko rule as normal, except:
1. Passes lift all ko bans (superko only stops repetitions where neither player passed in between).
2. Regardless of what passes occur in between or not, the game ends when a player passes in a position that player previously passed in. (and this is the only game end condition now. So in normal games it means that the game usually ends with 3 consecutive passes, not 2).
#1 is of course targeted at breaking the kinds of positions in this thread.
Intuition for #2 is to say that even if ko bans are lifted, we can still end the game in the case of cycles involving enough passes, because passes usually indicate one or both players have nothing better to do.
In normal cases with 3 passes, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 passes: "I have nothing I want to do, not even with ko bans lifted"
P1 passes: "I have nothing I want to do, not even with ko bans lifted - okay the game should end since neither player has useful things to do".
In cases with unbalanced repetition where only 1 player is passing while the other player cycles, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 plays some moves that force P1 to respond, but they only lead back to the same position where P1 passes originally.
P1 passes: "I still have nothing I want to do, and if the best that you, P2, could do even with all ko bans lifted and a free extra turn was merely to cycle back to the same position where I can pass yet again, then obviously you're just wasting time, the game should end now."
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
Re: Curious result in area scoring rule.
By beginning your post by "If you want to avoid this kind of pathology..." you seem quite careful and I agree with that.lightvector wrote:If you want to avoid this kind of pathology, but still break all cycles, guarantee that games are finite, and handle the "basic" situations the way that most players' intuitions think they should be handled (of course there are always still more complex rules beasts), you can use Bill Spight's innovation regarding ko bans and game end:
Use a superko rule as normal, except:
1. Passes lift all ko bans (superko only stops repetitions where neither player passed in between).
2. Regardless of what passes occur in between or not, the game ends when a player passes in a position that player previously passed in. (and this is the only game end condition now. So in normal games it means that the game usually ends with 3 consecutive passes, not 2).
#1 is of course targeted at breaking the kinds of positions in this thread.
Intuition for #2 is to say that even if ko bans are lifted, we can still end the game in the case of cycles involving enough passes, because passes usually indicate one or both players have nothing better to do.
In normal cases with 3 passes, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 passes: "I have nothing I want to do, not even with ko bans lifted"
P1 passes: "I have nothing I want to do, not even with ko bans lifted - okay the game should end since neither player has useful things to do".
In cases with unbalanced repetition where only 1 player is passing while the other player cycles, the "hand talk" is like:
P1 passes: "I have nothing I want to do *except* maybe I'm just waiting to recapture a ko and have no other non-suicidal moves"
P2 plays some moves that force P1 to respond, but they only lead back to the same position where P1 passes originally.
P1 passes: "I still have nothing I want to do, and if the best that you, P2, could do even with all ko bans lifted and a free extra turn was merely to cycle back to the same position where I can pass yet again, then obviously you're just wasting time, the game should end now."
As far as I am concerned it is not really a pathology but simply a consequence of the rule which does not hurt me for two reasons:
1) It will never happen in practice on a 19x19 board and I have even great doubt it can happen in practice on a 9x9 board.
2) On a smaller board this result seems even interesting and remind me the zugswang in chess. I you like very small boards what really harms by taking care of such possibility?
IOW it is for me only a curiosity of the rule as suggested by the title I chose.
Re: Curious result in area scoring rule.
There are some drawbacks with Bill's approach though. It doesn't seem to work well on 0-sided ko (reducing half point games to no-pass go by randomly stopping in one of the oscillating states). Also seems somewhat superfluous, considering three major types of repetition:
1. unbalanced repetition (not a thing in territory scoring, needs prevention for area scoring)
2. moonshine repetition (minor problem for both scoring, best prevented)
3. normal repetition (things like triple ko, no real problem for either scoring method)
If you handle type 1 by another rule, why bother with superko at all? Its remaining functionality is either miniscule (2) or outright undesired (3), at least for the Asian game. Even if used it seems better to just "minimal superko" (no repetition of the position of the last successive two passes).
1. unbalanced repetition (not a thing in territory scoring, needs prevention for area scoring)
2. moonshine repetition (minor problem for both scoring, best prevented)
3. normal repetition (things like triple ko, no real problem for either scoring method)
If you handle type 1 by another rule, why bother with superko at all? Its remaining functionality is either miniscule (2) or outright undesired (3), at least for the Asian game. Even if used it seems better to just "minimal superko" (no repetition of the position of the last successive two passes).
-
Gérard TAILLE
- Gosei
- Posts: 1346
- Joined: Sun Aug 23, 2020 2:47 am
- Rank: 1d
- GD Posts: 0
- Has thanked: 21 times
- Been thanked: 57 times
Re: Curious result in area scoring rule.
Now you have got the main idea can you resolve this new problem?
Assuming you use area counting and superko:
Can you build in the marked area an environment such that the best move is a white move at "b" ?
I confess it was not easy for me to solve this problem but eventually I managed to find a solution.
Assuming you use area counting and superko:
Can you build in the marked area an environment such that the best move is a white move at "b" ?
I confess it was not easy for me to solve this problem but eventually I managed to find a solution.